Vitamin D deficiency is highly prevalent among the Saudi population. Increased parathyroid hormone (PTH) secretion is an appropriate homeostatic response to correct the resultant hypocalcemia. However, not all vitamin D deficiency patients have increased PTH levels. This study determined the prevalence of a blunted PTH response to vitamin D deficiency among apparently healthy young Saudi women and assessed anthropometric and biochemical factors associated with this response by performing a secondary analysis of data obtained from a cross-sectional study conducted at the “Center of Excellence for Osteoporosis research.” Overall, 315 women (aged 20–45 years) with vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) levels <30 nmol/L) were included. They were divided into two groups according to the laboratory cutoff value of PTH (<7 or ≥7 pmol/L), and anthropometric and biochemical characteristics of both groups were compared. Women with a blunted PTH response (n = 62, 19.7%) had a significantly lower body mass index (BMI) () and smaller waist circumference (). They also had significantly higher serum 25(OH)D (), corrected serum calcium (), and phosphate () levels than those with an elevated PTH response (n = 253, 80.3%). Multiple logistic regression analysis showed that lower BMI (OR = 0.925; 95% CI: 0.949–0.987) and higher 25(OH)D (OR = 1.068; 95% CI: 1.014–1.124) and serum calcium (OR = 8.600; 95% CI: 1.614–45.809) levels were significantly associated with a blunted PTH response (R² = 0.178). A blunted PTH response to vitamin D deficiency is mainly observed among women with lower BMI. Higher serum calcium and 25(OH)D levels and lower BMI were significant predictors of a blunted PTH response, which may indicate that these subjects are adapting to lower 25(OH)D levels and maintaining normal calcium levels without the need to increase PTH secretion. The mechanisms underlying this adaptation are unclear, and future studies to explore these mechanisms are warranted.

中文翻译：

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维生素 D 缺乏症年轻沙特女性甲状旁腺激素反应迟钝的患病率和决定因素：一项横断面研究

维生素 D 缺乏症在沙特人口中非常普遍。甲状旁腺激素 (PTH) 分泌增加是纠正由此产生的低钙血症的适当稳态反应。然而，并非所有维生素 D 缺乏症患者的 PTH 水平都升高。本研究确定了明显健康的年轻沙特女性对维生素 D 缺乏症 PTH 反应迟钝的普遍性，并通过对从“中心卓越的骨质疏松症研究。” 总体而言，纳入了 315 名患有维生素 D 缺乏症（血清 25-羟基维生素 D（25（OH）D）水平 <30 nmol/L）的女性（20-45 岁）。根据PTH的实验室临界值将他们分为两组（< 7 或 ≥ 7 pmol/L)，并比较两组的人体测量学和生化特征。PTH 反应迟钝的女性（n  = 62, 19.7%) 的体重指数 (BMI) 显着降低（)和较小的腰围 (）。他们还具有显着更高的血清 25(OH)D (),校正血清钙 ()和磷酸盐 ()水平高于 PTH 反应升高的那些 ( n  = 253, 80.3%)。多元逻辑回归分析显示较低的 BMI (OR = 0.925; 95% CI: 0.949–0.987) 和较高的 25(OH)D (OR = 1.068; 95% CI: 1.014–1.124) 和血清钙 (OR = 8.600; 95 % CI: 1.614–45.809) 水平与迟钝的 PTH 反应显着相关 ( R ² = 0.178）。对维生素 D 缺乏的 PTH 反应迟钝主要见于 BMI 较低的女性。较高的血清钙和 25(OH)D 水平以及较低的 BMI 是 PTH 反应迟钝的重要预测因素，这可能表明这些受试者正在适应较低的 25(OH)D 水平并维持正常的钙水平，而无需增加 PTH 分泌. 这种适应的潜在机制尚不清楚，需要进一步研究探索这些机制。