We assume that 25(OH)D level >50 nmol/l is necessary for adequate parathyroid hormone (PTH) suppression in our population. The epidemiology of vitamin D status in Bulgarian population shows deficiency in 21.3 %, insufficiency in 54.5 % and sufficiency in 24.2 %. The mean level of 25(ОН)D for the Bulgarian population is 38.75 nmol/l (95 % CI, 38.00-39.49).
The aim of the present study was to investigate the vitamin D levels in Bulgaria and the prevalence of vitamin D deficiency depending on gender and age, as well as to define population-specific 25(OH)D sufficiency thresholds through the relationship with PTH.
This cross-sectional study was conducted in January-February 2012 and included 2,032 subjects in 12 regions-1,076 women (53 %) and 956 men (47 %), mean age 49.30 ± 14.75 years (20-80 years), divided into three age groups: young (20-44 years, n = 894), middle-aged (45-59 years, n = 534), and elderly (≥60 years, n = 604). 25(OH)D and PTH were measured in all subjects.
The mean level of 25(ОН)D was 38.75 nmol/l (95 % CI, 38.00-39.49). The men had significantly higher 25(ОН)D levels in comparison to women (41.51 nmol/l (95 % CI, 40.45-42.56) vs.36.29 nmol/l (95 % CI, 35.27-37.32), p < 0.05). We did not find significant differences in the 25(ОН)D levels between the three age groups. The prevalence of vitamin D deficiency was 21.3 %; insufficiency, 54.5 %; and sufficiency, 24.2 %. Deficiency was more prevalent in women (26.9 %) than in men (15.1 %), p < 0.001. PTH started to rise over the upper limit of the reference range at mean 25(OH)D 50 nmol/l. We assume that levels over 50 nmol/l are necessary for adequate PTH suppression.
The status of vitamin D in our country is worrisome, and it is largely underestimated. The defining of a vitamin D sufficiency levels may help the devising of adequate strategies for prevention and treatment in clinical practice.