PLOD1 and vitamin D deficiency: Subgroup analysis of geographical areas revealed that serum LH was significantly higher among the non-Asian population with vitamin D insufficiency/deficiency compared to the control group (WMD 2.16 IU/l; 95% CI 0.20 to 4.12; P = 0.031) with no evidence of heterogeneity (I2 = 9.3%, P = 0.294) (Table 2).