SERUM 25-HYDROXY VITAMIN D;

PARATHORMONE AND BONE MINERAL DENSITY: CO-RELATION IN CHILDREN

Abstract

Deficiency of vitamin D is an emerging issue in children worldwide. It has been
observed that all patients with vitamin D deficiency does not manifest clinical features or hyperparathyroid
response. In this study we have evaluated the interaction of serum vitamin D level,
parathyroid hormone (PTH) level and bone mineral density (BMD) in children. Objectives: Our
objectives were to determine the frequency of Vitamin D deficiency in children and association of
low serum D level with serum parathyroid level and bone mineral density (BMD). Study Design:
Descriptive cross sectional study. Period: June 2012 to May 2014. Setting: Pediatric and Orthopediatric
out-patient departments. Material & Methods: A total of 500 children up to 15 years
with low serum vitamin D level were enrolled to analyze the interaction of Serum vitamin D, PTH
and BMD. Patients were divided in groups on the basis of serum PTH. We have categorize the
deficiency of Vitamin D on the basis of level of 25OHD. It was defined as severe (25OHD ≤ 5
ng/ml), moderate (25OHD≤ 10 ng/ml) and mild (25OHD ≤ 20 ng/ml) and hyperparathyroidism
(SHPT) was valued if level >65 pg/ml. All children with 25OH ≤ 20 ng/ml were included and
association with SHPT and BMD were measured. Results: It has been observed that 30–40%
of patients with moderate and severe deficiency of vitamin D respectively had shown increased
level of PTH. Bone mineral density has demonstrated decline pattern from PTH Quartile 1to
Quartile 4 at all sites in children, with only minimal difference (decreasing trend) in serum
25OHD levels between these quartiles. The critical level of parathyroid hormone beyond which
BMD going to decline is 35 pg/ml. No demonstrable difference has been observed in BMD
within each PTH quartile according to categorization of Vitamin D Deficiency. Conclusions:
Around 40% of the patients having low serum vitamin D level demonstrated SHPT. Regarding
the BMD levels, it begins to decreases at PTH levels currently well thought-out to be normal.
So there is a need to re-define SHPT among different age groups considering the relationship
linking PTH and BMD. This may also affect guidelines regarding vitamin d supplementation in
patients with vitamin D deficiency.