OBJECTIVE: To determine the frequency of subclinical vitamin D deficiency in an ambulatory care setting.
METHODS: This was an observational study which measured 25 vitamin D levels in medical clinic patients. Patients with chronic renal failure, known osteomalacia and rickets were excluded. A total of 119 patients were evaluated. They were divided in three diagnostic categories based on their serum 25 vitamin D levels. Those with levels below 8 ng/ml were categorized to have severe deficiency, levels between 8 - 20 ng/ml as moderate deficiency and levels of 21-35 mg/ml as mild deficiency.
RESULTS: Of 119 patients, 92% had vitamin D deficiency. Their mean age was 44.3 +/- 18.3 years, with female to male ratio of 5:1. Sixty two percent (62%) had severe, 24% moderate and 8% had mild deficiency. Nearly half of all these patients (including those with severe deficiency) were asymptomatic. Whereas a low serum calcium, elevated phosphate and elevated alkaline phosphatase were reflective of severe deficiency. It was only an elevated iPTH that correlated with mild to moderate deficiency.
CONCLUSION: Subclinical vitamin D deficiency is extensive in the adult ambulatory care patients. Serum calcium, phosphate and alkaline phosphatase are poor markers of moderate to mild deficiency. A serum 25 vitamin D level and an iPTH are better biofunctional markers of this deficiency.
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