<prompt> Which of the following is best method for monitoring the treatment and resolution of vitamin D deficiency?Serum calcium levelsSerum phosphate levelsSerum vitamin D levelsSerum parathormone levels  <response>: Ans. a. Serum calcium levels Ref. Harrisons Principles of Internal Medicine 16th Edition 2249. The most specific screening test for vitamin D deficiency in otherwise healthy individuals is a serum 25OHD level. Radiologic features of vitamin D deficiency in children include a widened, expanded growth plate, characteristic ofrickets. A specific radiologic feature of osteomalacia, whether associated with phosphate wasting or vitamin D deficiency, ismilkmans fractures, pseudofractures, or Loosers zones.TREATMENT MONITORING OF VITAMIN D DEFICIENCY Daily intake of a multivitamin preparation that contains 400 IU of vitamin D is often insufficient to prevent vitamin D deficiency. Based on the observation that 800 IU of vitamin D, with calcium supplementation, decreases the risk of hip fractures in elderly women, 800 IU is considered to be a more appropriate daily dosage for prevention of vitamin D deficiency. The safety margin for vitamin D is large, and vitamin D toxicity is usually observed only in patients taking doses 40,000 IU daily. The most efficacious methods to monitor treatment and resolution of vitamin D deficiency are serum and urinary calcium measurements.- For patients who are vitamin D replete and are taking adequate calcium supplementation, the 24-h urinary calcium excretion should be in the range of 100 to 250 mg24 h.- Lower levels suggest problems with adhering to the treatment regimen or with absorption of calcium or vitamin D supplements. The 25OHD level can be re-measured to address the latter, although the half-life of this metabolite is long 3weeks and levels may continue to increase for many months on a stable regimen. Urinary calcium excretion 250 mg24 h predisposes to nephrolithiasis and should prompt a reduction in vitamin D dosage andor calcium supplementation. 