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54. What is adequate sun exposure for vitamin D synthesis?

Sunlight is the richest source for UV-B rays, which is required for endogenous

vitamin D synthesis. Exposure to sunlight between 1000 and 1500h is recom-

mended as the ratio of ultraviolet-B rays (UV-B) to UV-A rays is highest during

this period. Exposure of whole body in a bathing suit to one minimal erythemal

dose (MED) results in synthesis of approximately 10,000–20,000 IU of vitamin

D 3 , whereas exposure of 6–10 % of body (face and hands) to 0.5 MED provides

600–1000 IU of vitamin D 3. Minimal erythemal dose is defined as the amount

of exposure to UV-B rays which results in persistent perceptible redness of

skin, 24h after sun exposure. Redness which occurs immediately after sun

exposure and disappears within 3–5h is mainly caused by heat and does not

reflect adequate UV-B exposure. The approximate time for 1 MED is 4–10 min

for white-skinned individuals and 60–90 min for dark-skinned individuals.

55. How to treat vitamin D deficiency rickets–osteomalacia?

Various regimens have been advocated to treat vitamin D deficiency rickets–

osteomalacia. The recommended dose of vitamin D 3 (cholecalciferol) is

depicted in the table given below. Vitamin D 2 (ergocalciferol) is as effective as

vitamin D 3 in the treatment of vitamin D deficiency. These dosing schedules are

aimed to achieve and maintain 25(OH)D levels >30 ng/ml.

Age group Intensive phase therapy Maintenance therapy

0–1 year 60,000 IU once weekly for 6 weeks 400–1000 IU/day

or

2000 IU/day for 6 weeks

1–18 years 60,000 IU once weekly for 6 weeks 600–1000 IU/day

or

2000 IU/day for 6 weeks

Adults 60,000 IU once weekly for 8 weeks 1500–2000 IU/day

or

6000 IU/day for 8 weeks

In addition to vitamin D supplementation, adequate intake of calcium must be

ensured (30–75 mg/Kg/day of elemental calcium in three divided doses) to pre-

vent hungry bone syndrome in children with rickets–osteomalacia.

56. What is “stoss therapy”?

“Stoss therapy” (stossen in German means to push) involves administration

of massive doses of vitamin D to treat vitamin D deficiency rickets–

osteomalacia, particularly in those patients whose compliance to therapy

5 Rickets–Osteomalacia