Serum Alkaline Phosphatase Screening for Vitamin D Deficiency States

Objective: To determine whether serum vitamin D levels are correlated with serum levels of alkaline phosphatase or not.

Study Design: Cross-sectional, observational study.

Place And Duration Of Study: Multi-centre study, conducted at Liaquat National Hospital and Medical College, National Medical Centre and Medicare Hospital, Karachi, from January to October 2009.

Methodology: Patients attending the Orthopaedic OPDs with complaints of pain in different body regions and serum vitamin D3 levels of ² 30 ng/ml were included in the study. Patients with vitamin D deficiency were further categorized into mild deficiency or insufficiency (vit. D3 = 20-29 ng/ml), moderate deficiency (vit. D3 = 5 - 19 ng/ml) and severe deficiency forms (vit. D3 < 5 ng/ml). Pearson correlation was applied to test the correlation of serum alkaline phosphatase levels with serum vitamin D3 levels. P-value < 0.05 was considered to be significant.

Results: Out of 110 samples, 26 had mild (23%), 61 had moderate (55%) and 21 had severe (19.1%) vitamin D deficiencies. All of the patients in the three groups had alkaline phosphatase with in normal limits and the total mean value of the enzyme was 135.97 ± 68.141 U/L. The inter group comparison showed highest values of alkaline phosphatase in the moderate vitamin D deficiency group. The correlation coefficient of alkaline phosphatase and serum vitamin D3 levels was r =0.05 (p =0.593).

Conclusion: Serum vitamin D3 levels may not be correlated with increased serum alkaline phosphatase levels. Therefore, alkaline phosphatase may not be used as a screening test to rule out vitamin D deficiency.