PMC5796911_01
Diarrhea response and fluctuation of laboratory values prior to and post calcium replacement. Stool output (A) does not vary with blood levels of tacrolimus (C) but fluctuates with blood concentrations of Ca2+ ([Ca2+]) (B) on three occasions and via two routes of administration. Upon switch to a dairy-free diet, [Ca2+] reduces and diarrhea occurs. With intravenous CaCl2, [Ca2+] rises and stool output declines. With oral CaCO3, [Ca2+] rises again and stool output yet declines again. The corresponding alterations in other laboratory values are shown in (D,E). The values between the upper lines (upper normal limits) and lower lines (lower normal limits) are normal, whereas the values above the upper lines are elevated and those below the lower lines are reduced. The two gray areas illustrate the periods in which the patient was receiving calcium therapies. The form of calcium salts and their doses administered are indicated in the black boxes. It is likely that under a negative status of calcium balance, the diarrhea-combating ability of the divalent mineral is compromised, and the responsiveness to immunomodulators is lost. As a result, disease is "flared up" and the patient becomes diarrheic. Diarrhea will temporarily be halted upon normalization of calcium level. However, the disease will relapse and will not enter a permanent remission state unless a normal positive calcium balance is restored.
fped-06-00007-g001.jpg
PMC5796911_01_fped-06-00007-g001.jpg
F1
However, for the 6 months prior to this admission, social issues gradually led to interruption of this therapy with recurrence of diarrhea (Figure 1A) and weight loss. His laboratory values are shown in Figures 1B-E. However, his diarrhea (Figure 1A) and metabolic acidosis (Figure 1E) remained while hypokalemia (Figure 1D) worsened. Despite good therapeutic blood levels of tacrolimus (Figure 1C), the diarrhea persisted (Figure 1A). Remarkably, as his serum-ionized Ca2+ normalized, his diarrhea resolved (Figure 1A). The diarrhea resolved within 2 days of administration of oral calcium carbonate suspension (1.3 mEq elemental Ca2+/kg/day) (Figure 1A).