the first objective of the study is to characterize calcium flux in patients during the immediate postoperative period so as to verify the findings from the original article using a different group of patients.1 the second and third objectives are to compare the new infusion regimen with the original one looking at both treatment efficacy and calcium excursions outside the target range of 23  mmol / l , respectively . for this study , efficacy is determined by the duration of hypocalcaemia , total amount of calcium gluconate infused , and the time period of infusion . excursions are measured by the percentage of the treatment period where the calcium level was below , above , or outside the target range , as well as the peak and trough calcium during treatment . only patients diagnosed with secondary hyperparathyroidism of renal origin ( icd10cm diagnosis code n25.81 ) who underwent parathyroidectomy with or without autotransplantation were included . in addition , they had to be started on an intravenous calcium gluconate infusion after surgery with either the original or new regimen . patients younger than 16  years and pregnant women were excluded as physiological differences in skeletal metabolism would make the study data difficult to interpret . treatment with bisphosphonates , calcitriol and calcium supplementation did not exclude patients from the study . however , usage within the 6  months prior to surgery and during the immediate postoperative period was noted . this study was done with prior ethics approval from the malaysian ministry of health research ethics committee ( kkm / nihsec / p15617 ) in accordance with current guidelines on good clinical practice and the declaration of helsinki , and was registered with the malaysian national medical research register ( nmrr1555424819 ) . the period of data collection was from 20112015 , during which the same surgical team was responsible for the care of all patients . cases for the period of 20112014 were managed using the original infusion regimen while those from 20132015 were on the novel regimen . an overlap period of about six months was used to allow the staff to gain confidence in the new regimen . u / l , dimension rxl max , siemens healthcare diagnostics , newark , de , usa ) was measured without isoenzyme determination , and included only if done in the 6month period prior to surgery . pmol / l , 539  pg / ml , immunoradiometric assay , scantibodies laboratory , santee , ca , united states ) value used was the most recent reading taken prior to surgery . mmol / l , 8.6010.20  mg / dl , dimension rxl max ) was the calcium level corrected for serum albumin using payne 's method.10 the patient age , height , and weight were at operation date , while the adenoma volume was estimated on ultrasonography , or from the histology report of the surgical specimen when available . symptoms such as perioral numbness , tingling , muscle weakness or cramps , were noted from the clinical records if present concurrent to the periods of biochemical hypocalcaemia . the relevant preoperative factors are compared between the two regimens using an independent samples ttest for continuous variables ( age , alp , pth , adenoma volume ) , or a  test with yates ' continuity correction where appropriate for categorical variables ( gender , ethnicity , bisphosphonate pretreatment , calcitriol pretreatment ) . objective 1 
 calcium flux 
  the determination of calcium flux follows the methodology detailed in the original study for the infusion regimen.1 calcium influx ( mmol / h ) is calculated by multiplying the infusion rate ( ml / h ) with the conversion factor ( 0.2325  mmol / ml ) . the rate of change in the extracellular pool ( mmol / h ) is calculated by taking the difference in serum calcium ( mmol / l ) between two consecutive readings divided by the time difference ( 4  h ) and multiplied by total extracellular fluid volume ( ecf ) ( 15  l in a normal adult ) . the calculated efflux ( mmol / h ) is thus the difference between the rate of change in the extracellular calcium pool and influx rate . the peak efflux rate ( per ) and timing are obtained for each subject , ignoring readings immediately after dialysis sessions . the per was also recalculated using the ecf estimated from abraham 's method and compared with the original per using linear regression.11 
  whenever the calculated per is greater than 3  mmol / h , this may suggest a sampling error in the calcium readings , most commonly due to prolonged tourniquet application when drawing blood . the actual values are then inspected and the elevated per associated with isolated high calcium readings are treated as missing values and replaced on a  last valid observation carried forward basis . outliers are detected by plotting cook 's distance against centred leverage value for the pertiming regression , and variances displayed using a residual plot . a scatterplot of per against time is charted , along with linear regression to see if a relationship exists between these variables . in addition , the per and timing are compared for both regimens using bar charts and an independent samples ttest . levene 's test is used to check for equality of variances to determine the appropriate type of ttest to use . if a significant difference is detected in per between regimens , a univariate general linear model analysis of variance ( glmanova ) is performed with per as the dependent variable , the type of regimen as the betweensubjects factor , with alp , pth , calcitriol pretreatment , bisphosphonate pretreatment , and total calcium infused as covariates . oral calcium pretreatment is not used as a covariate as every subject received it at our centre . posthoc power is calculated using g*power 3.1 for each statistical test.12 
 objective 2 
 treatment efficacy 
  the duration of hypocalcaemia , total amount of calcium gluconate infused , and the time period of infusion are compared in a similar manner to per . objective 3 
 calcium excursions 
  the percentage of the treatment period where the calcium level was below , above , or outside the target range , as well as the peak and trough calcium during treatment are compared in a similar manner to per . subjects were divided into two groups depending on whether they reported symptoms suggestive of hypocalcaemia , and were compared based on per and trough calcium using an independent samples ttest . only patients diagnosed with secondary hyperparathyroidism of renal origin ( icd10cm diagnosis code n25.81 ) who underwent parathyroidectomy with or without autotransplantation were included . in addition , they had to be started on an intravenous calcium gluconate infusion after surgery with either the original or new regimen . patients younger than 16  years and pregnant women were excluded as physiological differences in skeletal metabolism would make the study data difficult to interpret . treatment with bisphosphonates , calcitriol and calcium supplementation did not exclude patients from the study . however , usage within the 6  months prior to surgery and during the immediate postoperative period was noted . this study was done with prior ethics approval from the malaysian ministry of health research ethics committee ( kkm / nihsec / p15617 ) in accordance with current guidelines on good clinical practice and the declaration of helsinki , and was registered with the malaysian national medical research register ( nmrr1555424819 ) . the period of data collection was from 20112015 , during which the same surgical team was responsible for the care of all patients . cases for the period of 20112014 were managed using the original infusion regimen while those from 20132015 were on the novel regimen . an overlap period of about six months was used to allow the staff to gain confidence in the new regimen . u / l , dimension rxl max , siemens healthcare diagnostics , newark , de , usa ) was measured without isoenzyme determination , and included only if done in the 6month period prior to surgery . pmol / l , 539  pg / ml , immunoradiometric assay , scantibodies laboratory , santee , ca , united states ) value used was the most recent reading taken prior to surgery . serum calcium ( reference interval : 2.152.55  mmol / l , 8.6010.20  mg / dl , dimension rxl max ) was the calcium level corrected for serum albumin using payne 's method.10 the patient age , height , and weight were at operation date , while the adenoma volume was estimated on ultrasonography , or from the histology report of the surgical specimen when available . symptoms such as perioral numbness , tingling , muscle weakness or cramps , were noted from the clinical records if present concurrent to the periods of biochemical hypocalcaemia . the relevant preoperative factors are compared between the two regimens using an independent samples ttest for continuous variables ( age , alp , pth , adenoma volume ) , or a  test with yates ' continuity correction where appropriate for categorical variables ( gender , ethnicity , bisphosphonate pretreatment , calcitriol pretreatment ) . objective 1 
 calcium flux 
  the determination of calcium flux follows the methodology detailed in the original study for the infusion regimen.1 calcium influx ( mmol / h ) is calculated by multiplying the infusion rate ( ml / h ) with the conversion factor ( 0.2325  mmol / ml ) . the rate of change in the extracellular pool ( mmol / h ) is calculated by taking the difference in serum calcium ( mmol / l ) between two consecutive readings divided by the time difference ( 4  h ) and multiplied by total extracellular fluid volume ( ecf ) ( 15  l in a normal adult ) . the calculated efflux ( mmol / h ) is thus the difference between the rate of change in the extracellular calcium pool and influx rate . the peak efflux rate ( per ) and timing are obtained for each subject , ignoring readings immediately after dialysis sessions . the per was also recalculated using the ecf estimated from abraham 's method and compared with the original per using linear regression.11 
  whenever the calculated per is greater than 3  mmol / h , this may suggest a sampling error in the calcium readings , most commonly due to prolonged tourniquet application when drawing blood . the actual values are then inspected and the elevated per associated with isolated high calcium readings are treated as missing values and replaced on a  last valid observation carried forward basis . outliers are detected by plotting cook 's distance against centred leverage value for the pertiming regression , and variances displayed using a residual plot . a scatterplot of per against time is charted , along with linear regression to see if a relationship exists between these variables . in addition , the per and timing are compared for both regimens using bar charts and an independent samples ttest . levene 's test is used to check for equality of variances to determine the appropriate type of ttest to use . if a significant difference is detected in per between regimens , a univariate general linear model analysis of variance ( glmanova ) is performed with per as the dependent variable , the type of regimen as the betweensubjects factor , with alp , pth , calcitriol pretreatment , bisphosphonate pretreatment , and total calcium infused as covariates . oral calcium pretreatment is not used as a covariate as every subject received it at our centre . posthoc power is calculated using g*power 3.1 for each statistical test.12 
 objective 2 
 treatment efficacy 
  the duration of hypocalcaemia , total amount of calcium gluconate infused , and the time period of infusion are compared in a similar manner to per . objective 3 
 calcium excursions 
  the percentage of the treatment period where the calcium level was below , above , or outside the target range , as well as the peak and trough calcium during treatment are compared in a similar manner to per . subjects were divided into two groups depending on whether they reported symptoms suggestive of hypocalcaemia , and were compared based on per and trough calcium using an independent samples ttest . case records for patients with the icd10cm n25.81 diagnosis from march 2011 to april 2014 who were on the original infusion regimen were screened , of which 51 satisfied the inclusion and exclusion criteria . a further 34 patients on the new regimen from october 2013 to june 2015 were similarly included . patient demographics were as follows : age ( 2167 , mean 47  years ) ; male ( 34 ) , female ( 51 ) ; malay ( 58 ) , chinese ( 20 ) , indian ( 6 ) , others ( 1 ) . twentyfour out of eightyfive ( 28% ) patients were pretreated with bisphosphonates , and none were on cinacalcet . there was no significant difference between bisphosphonate and nonbisphosphonate groups in the trough calcium ( t  =  1.91 , p  =  0.06 , mean difference  =  0.14  mmol / l , posthoc power 51.9% ) or per ( t  =  1.48 , p  =  0.14 , mean difference  =  0.31  mmol / h , posthoc power 32.3% ) . most patients were on stable doses of calcitriol ( 0.52  g / day ) and calcium carbonate ( 12  g elemental calcium per day ) prior to surgery , which was continued during the postoperative period . relevant preoperative factors are compared between both regimens and no significant differences were found ( table  1 ) . objective 1 
 calcium flux 
  summary comparing a selection of preoperative factors using either an independent samples ttest or a  test ( n  =  85 ) alp , alkaline phosphatase ; bisphos prerx , bisphosphonate pretreatment ; pth , parathyroid hormone ; vit . continuity correction applied for 22 contingency tables the mean per from the extracellular calcium pool was 2.43  mmol / h ( sd 0.87 ) , occurring 30.0  h ( sd 47.7 ) postoperatively . the per calculated using the ecf estimated from abraham 's method essentially mirrored the per calculated using a standard 15  l volume ( pearson 's correlation coefficient  =  0.95 ) . as the weight of the subjects and their estimated ecf can vary significantly as a result of dialysis , a decision was made to only use the per based on standard extracellular fluid volumes . a scatterplot of per against timing of peak efflux suggests a linear relationship between the variables . four clear outliers ( old regimen : 41 , 48 , 49 ; new regimen : 73 ) were identified on a plot of cook 's distance against centred leverage value . on reviewing the case records , the infusion regimen for patients 41 and 48 were undertitrated initially resulting in early hypocalcaemia . patient 49 had status epilepticus as an adverse reaction to a pethidine injection and was kept in intensive care for an extended period . a standardized residual plot was charted for per , confirming both homoscedasticity and normality aside from the outliers identified . this was further supported by a nonsignificant kolmogorovsmirnov test ( z  =  1.04 , p  =  0.23 ) against a normal distribution . with outliers excluded , the scatterplot was recharted with a regression line through the origin ( fig . the adjusted rsquare was determined to be 0.64 ( se 1.53 , p  <  0.001 for f change ) , suggesting a large correlation between per and timing of peak calcium efflux.13 the regression equation can be represented as per ( mmol / h )  =  0.073 ( 95% ci 0.0610.085 )  peak efflux time ( h ) . the independent samples ttest and bar charts showed that per was lower ( 2.16 vs 2.56 ; 0.40  mmol / h difference , p  =  0.03 , 95% ci 0.030.77 ) and occurred earlier ( 17.6 vs 23.2 ; 5.6  h difference , p  =  0.13 , 95% ci 1.712.9 ) for the new regimen ( fig . the differences were significant for per but not for timing as the variability in the latter was fairly high , while the respective posthoc powers were 60.4% and 29.3% . bar charts comparing the original and new regimens for the ( a ) peak efflux rate and ( b ) timing . summary results for the independent samples ttest comparing the original and new regimens for selected parameters glmanova showed that the type of infusion regimen had the largest effect on per ( partial etasquared  =  0.568 ) , while the effect size for total calcium infused was three times that of the remaining four covariates combined ( table  3 ) . the interaction term between the type of infusion regimen and total calcium infused was fairly weak ( partial etasquared  =  0.010 ) . objective 2 
 treatment efficacy 
  summary results for glmanova comparing the original and new regimens against per with selected covariates alp , alkaline phosphatase ; bisphos . the glmanova model is built without intercept as the mean per difference was already tested in table  2 . the sum of squares is a measure of variability analogous to a standard deviation or variance in a population . the partial eta squared is a measure of effect size , which describes the proportion of variability in the per attributed to that factor . the observed power is the probability of correctly rejecting the null hypothesis that the factor has no effect on the per . the independent samples ttest comparing the original and new regimens for the duration of hypocalcaemia , total amount of calcium gluconate infused , and the time period of infusion were all significantly different ( fig . the new regimen had a shorter duration of hypocalcaemia ( 28.9 vs 66.4 ; 37.5  h difference , p  =  0.04 , 95% ci 2.472.5 ) , required less calcium infusion ( 67.7 vs 127.2 ; 59.5  mmol elemental calcium difference , p  =  0.02 , 95% ci 8.1110.9 ) for a shorter duration ( 57.3 vs 102.9 ; 45.6  h difference , p  =  0.001 , 95% ci 18.972.3 ) . the posthoc power of the three tests were , respectively , 51.0% , 55.2% , and 87.4% . objective 3 
 calcium excursions 
  bar charts comparing the original and new regimens for the ( a ) duration of hypocalcaemia , ( b ) total amount of calcium gluconate infused , and ( c ) the time period of infusion . of the 48 patients on the original regimen , 22 ( 46% ) had excursions below 2  mmol / l , 15 ( 31% ) had excursions above 3  mmol / l , and 32 ( 67% ) had excursions outside of the target range of 23  mmol / l . mean duration of low excursions was 25.8% ( sd 21.4 ) , mean duration of high excursions was 7.6% ( sd 4.7 ) , and mean duration of all excursions was 21.3% ( sd 19.8 ) of the treatment periods . mean trough calcium was 2.06  mmol / l ( sd 0.26 ) , and mean peak calcium was 2.86  mmol / l ( sd 0.33 ) . of the 33 patients on the new regimen , 11 ( 33% ) had excursions below 2 mmol / l , 7 ( 21% ) had excursions above 3  mmol / l , and 17 ( 52% ) had excursions outside of the target range of 23  mmol / l . mean duration of low excursions was 25.0% ( sd 20.5 ) , mean duration of high excursions was 14.8% ( sd 13.8 ) , and mean duration of all excursions was 22.3% ( sd 21.0 ) of the treatment periods . mean trough calcium was 2.09  mmol / l ( sd 0.24 ) , and mean peak calcium was 2.83  mmol / l ( sd 0.42 ) . the independent samples ttest comparing the original and new regimens for the percentage of the treatment period where the calcium level was below , above , or outside the target range ( fig . 3a  c ) , as well as the peak and trough calcium during treatment were all nonsignificant ( fig . the posthoc power of the five tests were , respectively , 5.3% , 86.4% , 5.5% , 14.4% , and 75.5% . bar charts comparing the original and new regimens for ( a ) low , ( b ) high , and ( c ) total calcium excursions . bar charts comparing the original and new regimens for the ( a ) peak and ( b ) trough calcium during treatment . as the new regimen had a number of high excursions ( fig . 3b ) , a closer look was taken at the pattern of individual readings to determine the cause ( table  s1 ) . of the eight patients who had high excursions , three of these were due to possible errors in the calcium reading . the remaining five had calcium levels already above the normal range immediately after surgery , and when the infusion was started , this caused the level to rise above the threshold of 3 mmol / l within 12  h. per was found to be higher ( 2.91 vs 2.25  mmol / h , p  =  0.015 ) and trough calcium lower ( 1.92 vs 2.12  mmol , p  =  0.002 ) in those who reported symptoms suggestive of hypocalcaemia . the model of calcium flux used in the original study simplifies the physiological processes that occur in the postoperative period by considering only the total influx and efflux from the extracellular compartment.1 the results from this study support the findings from the original one in that the peak efflux time was strongly correlated with the per ( adjusted rsquare 0.64 , p  <  0.001 ) . the second finding was that the magnitude of per was significantly lower with the new regimen ( 0.40  mmol / h difference ) . in addition , the relatively large effect size for total calcium infused showed that the amount of calcium which is pumped into the patient is far more important in determining the amount of calcium efflux compared to the subject 's bone activity ( alp ) , hormonal levels ( pth ) , and pretreatment with either vitamin d or bisphosphonates . this is particularly interesting given that these factors were previously found to significantly affect poh.14 , 15 
  the weak interaction between total calcium infused and the type of regimen showed that the effect on per caused by the amount of calcium infused is independent of the regimen used . this in turn suggests that the driving effect of calcium infusion on per reflects an underlying physiological process rather than an idiosyncrasy of the regimens themselves . taken together , we see that the more aggressive the calcium replacement , the greater the efflux from the extracellular compartment and the more prolonged the time course of calcium movements . this means that calcium fluxes after parathyroid surgery for rhp are mostly supplydriven from the infusion regimen rather than demanddriven from poh . another point to note is that although the mean peak calcium levels for both regimens were comparable ( table  2 , fig .  4 ) , high excursions in the new regimen were solely due to starting the calcium infusion when perioperative serum calcium was already above the normal range furthermore , the patient who was mistakenly started on 10  ml / h ( 2.3  mmol / h ) immediately after surgery ( patient 73 , table supp1 ) had a prolonged high excursion of 88.2% of the treatment period indicating that this was far above the demands imposed by the physiological calcium changes after surgery . we chose a target serum calcium of 23  mmol / l ( 812  mg / dl ) instead of trying to keep it within the normal range of 2.12.6  mmol / l ( 8.410.4  mg / dl ) as patients are usually asymptomatic or mildly symptomatic within these bounds.16 , 17 tightening the target range requires more frequent calcium monitoring , and with more aggressive intervention there is always the risk of rebound changes in the opposite direction as observed in this study . when comparing the efficacy of the new regimen against the original , we see that this required significantly less calcium infused over a shorter period , and yet resulted in a reduced duration of hypocalcaemia . this is because a structured titration regimen is superior to an unstructured one in treating poh as the adjustments are often made by the oncall junior doctor after office hours . the lower requirement for calcium infusion means that disruption to a patient 's metabolic state as reflected by the per is minimised . this in turn results in an earlier peak efflux time , and a shortening of the period of calcium disturbance . hence it follows that if we adopt a more conservative infusion regimen , we could reduce morbidity , abbreviate the period of intensive calcium monitoring , shorten hospital stay , and lower overall costs . the findings from this study strongly suggest that early aggressive calcium replacement as commonly practiced in malaysia is unnecessary and in some cases may lead to significant hypercalcemia . we recommend that when the new regimen is used , the infusion should not be started immediately after surgery unless the calcium level is below the upper limit of the normal range for the local laboratory ( table  4 ) . this gives a margin of safety as the documented rise in serum calcium did not exceed 0.5  mmol / l ( 2  mg / dl ) in our study ( table supp1 ) . if hypocalcaemia persists 6  days after surgery , discontinue infusion and continue monitoring for a further 24  h. the value of 2.55  mmol / l ( 10.2  mg / dl ) can be replaced with the upper limit of the normal range for the local laboratory . the main limitation of this study is that data were collected retrospectively , thus precluding any attempt at randomization . data collection for both regimens occurred at different time periods thus raising the possibility of institutional changes over the years , which can give rise to sampling bias . this was , however , mitigated by the fact that surgery and management of patients at both time periods was under a single primary surgeon at the same hospital . the treatment of outliers in this study followed the same procedure as in the original study and special care was taken to avoid selective exclusion which can bias the results.1 , 18 for each outlier identified on statistical testing , the corresponding case records were inspected to determine whether a valid reason was present to exclude that particular case . although a number of isolated high calcium readings were detected through their effect on per , this was not taken as a reason to reject the rest of the data from that patient as previous studies have shown that up to 20% of calcium readings can be erroneous.19 when comparing the efficacy of the new regimen against the original , we see that this required significantly less calcium infused over a shorter period , and yet resulted in a reduced duration of hypocalcaemia . this is because a structured titration regimen is superior to an unstructured one in treating poh as the adjustments are often made by the oncall junior doctor after office hours . the lower requirement for calcium infusion means that disruption to a patient 's metabolic state as reflected by the per is minimised . this in turn results in an earlier peak efflux time , and a shortening of the period of calcium disturbance . hence it follows that if we adopt a more conservative infusion regimen , we could reduce morbidity , abbreviate the period of intensive calcium monitoring , shorten hospital stay , and lower overall costs . the findings from this study strongly suggest that early aggressive calcium replacement as commonly practiced in malaysia is unnecessary and in some cases may lead to significant hypercalcemia . we recommend that when the new regimen is used , the infusion should not be started immediately after surgery unless the calcium level is below the upper limit of the normal range for the local laboratory ( table  4 ) . this gives a margin of safety as the documented rise in serum calcium did not exceed 0.5  mmol / l ( 2  mg / dl ) in our study ( table supp1 ) . if hypocalcaemia persists 6  days after surgery , discontinue infusion and continue monitoring for a further 24  h. the value of 2.55  mmol / l ( 10.2  mg / dl ) can be replaced with the upper limit of the normal range for the local laboratory . the main limitation of this study is that data were collected retrospectively , thus precluding any attempt at randomization . data collection for both regimens occurred at different time periods thus raising the possibility of institutional changes over the years , which can give rise to sampling bias . this was , however , mitigated by the fact that surgery and management of patients at both time periods was under a single primary surgeon at the same hospital . the treatment of outliers in this study followed the same procedure as in the original study and special care was taken to avoid selective exclusion which can bias the results.1 , 18 for each outlier identified on statistical testing , the corresponding case records were inspected to determine whether a valid reason was present to exclude that particular case . although a number of isolated high calcium readings were detected through their effect on per , this was not taken as a reason to reject the rest of the data from that patient as previous studies have shown that up to 20% of calcium readings can be erroneous.19 based on the results from this study , we found that the new calcium infusion regimen was superior to the original one in that it required a shorter treatment period and resulted in less hypocalcaemia . we also found that early aggressive calcium replacement is unnecessary and raises the risk of rebound hypercalcaemia . table s1 a selection of calcium readings from patients on the new infusion regimen who had high excursions .
abstractaimcalcium infusion is used after parathyroid surgery for renal hyperparathyroidism to treat postoperative hypocalcaemia . 
 we compared a new infusion regimen to one commonly used in malaysia based on 2003  k / doqi guidelines.methodsretrospective data on serum calcium and infusion rates was collected from 20112015 . 
 the relationship between peak calcium efflux ( per ) and time was determined using a scatterplot and linear regression . a comparison between regimens 
 was made based on treatment efficacy ( hypocalcaemia duration , total infusion amount and time ) and calcium excursions ( outside target range , peak and trough calcium ) using bar charts and an unpaired ttest.resultsfiftyone and 34 patients on the original and new regimens respectively were included . 
 mean per was lower ( 2.16 vs 2.56  mmol / h ; p  =  0.03 ) and occurred earlier ( 17.6 vs 23.2  h ; p  =  0.13 ) for the new regimen . both scatterplot and regression showed a large correlation between per and time ( rsquare 0.64 , se 1.53 , p  <  0.001 ) . 
 the new regimen had shorter period of hypocalcaemia ( 28.9 vs 66.4  h , p  =  0.04 ) , and required less calcium infusion ( 67.7 vs 127.2  mmol , p  =  0.02 ) for a shorter duration ( 57.3 vs 102.9  h , p  =  0.001 ) . 
 calcium excursions , peak and trough calcium were not significantly different between regimens . 
 early postoperative high excursions occurred when the infusion was started in spite of elevated perioperative calcium levels.conclusionthe new infusion regimen was superior to the original in that it required a shorter treatment period and resulted in less hypocalcaemia . 
 we found that early aggressive calcium replacement is unnecessary and raises the risk of rebound hypercalcemia .