Association of Low Vitamin D and Intact Parathyroid Hormone (iPTH) in Nepalese Population: When Does iPTH Exactly Rise?

Abstract

Vitamin D deficiency is a global public health concern, which provokes bone demineralization and weakening. In response to the decreased vitamin D level, calcium stores worn out. The homeostatic effect of compensatory hyperparathyroidism in vitamin D deficiency incites variable discrepancies in different population. This study intends to decipher the transition point of parathyroid hormone (PTH) in relation to levels of vitamin D in Nepalese population. A cross-sectional study was carried out at Tribhuvan University Teaching Hospital, Nepal. Serum calcium, phosphorus, intact PTH and 25-hydroxy vitamin D levels were assayed in Abbott ARCHITECT Integrated System. A correlation plot of PTH and vitamin D was analyzed in SPSS version 22.0. Using LOWESS (Locally Weighted Scatter plot Smoothing) method, the relation between these variables was presented graphically. Among 281 individuals, 30.2% had vitamin D levels below 20 ng/ml. There was an archetypical transition in the PTH levels in concert with the decrease in vitamin D level marked by two inflection points viz. 18.5 and 42.0 ng/ml. Our findings suggest that to augment overall health and avert weakness due to vitamin D deficiency, the levels of vitamin D should be maintained above 42.0 ng/ml in our population.