Endocrine Abstracts

Introduction: Vitamin D deficiency is very common in Northern Europe. Recently, we developed an equation to calculate the vitamin D deficit, based on the serum 25-OH vitamin D₃ (25OHD₃) level and body weight: vitamin D deficit (IU)=40×(75−serum 25OHD₃)×body weight. The calculated deficit gives the amount of cholecalciferol that is required to raise the serum 25OHD₃ level to the target of 75 nmol/l.

Objective: To cross-validate the vitamin D deficit calculation procedure.

Materials and methods: Fifty subjects (age range 24–74 years, female/male ratio 2.8:1, body weight 45–230 kg) with vitamin D deficiency (defined as a serum vitamin D < 50 nmol/l) were treated with oral, solubilised Cholecalciferol^FNA 50.000 IE three times a week until the calculated cumulative dose was reached. Serum creatinine, phosphate, albumin, PTH, 25OHD₃ were measured at baseline and 10 days after the final dose of cholecalciferol.

Results:: Of 78% had severe vitamin D deficiency (25OHD₃ <30 nmol/l). The calculated cumulative dose ranged from 75.000–300.000 IU. Treatment was completed within 2 weeks in all patients. Mean serum 25OHD₃ increased from 26.4±11.8 to 76.7±21.4 nmol/l (mean±S.D). Ninety percent of the patients reached a serum 25OHD₃ >50 nmol/l. Vitamin D intoxication, defined as a serum level >220 nmol/l, was not observed. The highest post-treatment level was 148 nmol/l. Serum creatinine increased slightly, whereas serum calcium, phosphate, albumin and PTH levels did not change significantly.

Conclusion: The equation predicting the cholecalciferol loading dose required for rapid correction of vitamin D deficiency is effective and can be safely used in daily practice.