TABLE 1.

Overview of available vitamin D preparations, adapted to Prietl B. et al. (4) indicated usual dosage recommendations apply to non-ICU patients.

	Daily dose	Indication	Overdose side effects	Half-life	Costs
Native vitamin D
Unhydroxylated, inactive vitamin D3 Cholecalciferol Calcidiol/Calciol Very stable	400–4,000 IU	Vitamin D deficiency, osteoporosis, hypoparathyroidism, rickets prophylaxis.	Rarely hypercalcemia, hypercalciuria	Circulating: 2 days functional: 2–3 months	€
Unhydroxylated, inactive vitamin D2 Ergocalciferol Vitamin D2 Less stable during storage, cooking/baking	400–4,000 IU			Circulating: 2 days functional: 2 months or less (33)	€
Calcifediol	30–60 μg	Hyperparathyroidism, Vit D deficiency, renal failure CKD 3–4	Hypercalcemia, hypercalciuria	∼2 weeks
Active vitamin D
Hydroxylated active vitamin D 1,25(OH)2 D3 (calcitriol) 1,α(OH)D3 (alfacalcidol)	0.25–1.0 μg	Advanced kidney disease with secondary hyperparathyroidism, (pseudo) hypoparathyroidism, not alone in vitamin D deficiency.	Narrower therapeutic range: hypercalcemia, hyperphosphatemia, hypercalcuria, nephrocalcinosis.	15 h	€€
Other active vitamin D analogs: Analogs to vitamin D2: Paricalcitol, doxercalciferol Analogs to vitamin D3: Falecalcitriol, maxacalcitol		Advanced renal disease with secondary hyperparathyroidism,	Hypercalcemia possible, but less common than with other active forms	∼15 h	€€€

Calcidiol is the storage form of vitamin D from which calcitriol is produced on demand and has the highest half-life of 3 weeks. CKD, chronic kidney disease.