Table 1.

Classification of vitamin D levels (serum 25(OH)D levels): (3–5, 12, 27–39).

Classification	Nanograms	Nanomoles	Recommended D
Danger of toxicity	>100 ng/ml*	>250 nmol/l
Normal or optimal	>30 ng/ml	>75 nmol/l	400–4,000 IU/day
Insufficient	21–29 ng/ml	51–74 nmol/l	4,000–6,000 IU/day
Deficient	11–20 ng/ml	26–50 nmol/l	7,000 IU/day
Severely deficient (often not distinguished from deficient)	<10 ng/ml	25 nmol/l	10,000 IU/day x 1 month or 500,000 IU x 1

^*some sources found that 150 ng/ml was not harmful.