Shahidzadeh Yazdi Zhinous, Streeten Elizabeth A, Whitlatch Hilary B, Bargal Salma A, Beitelshees Amber L, Taylor Simeon I
Department of Medicine, Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
JCEM Case Rep. 2024 Jun 28;2(7):luae095. doi: 10.1210/jcemcr/luae095. eCollection 2024 Jul.
Although clinical guidelines recommend measuring total plasma 25-hydroxyvitamin D (25[OH]D) to assess vitamin D (VitD) status, this index does not account for 3-fold inter-individual variation in VitD binding protein (VDBP) level. We present 3 individuals with total plasma 25(OH)D levels of 10.8 to 12.3 ng/mL (27-30.7 nmol/L). Because Endocrine Society guidelines define VitD deficiency as 25(OH)D ≤ 20 ng/mL (50 nmol/L), all 3 would be judged to be VitD deficient. VitD3 supplementation increased 25(OH)D to the range of 31.7 to 33.8 ng/mL (79.1-84.4 nmol/L). Patient #1 exhibited secondary hyperparathyroidism; VitD3 supplementation decreased parathyroid hormone (PTH) by 34% without a clinically significant change in PTH levels in the other 2 individuals. Thus, 25(OH)D level did not distinguish between the 1 patient who had secondary hyperparathyroidism and the 2 who did not. We therefore inquired whether VitD metabolite ratios (which are VDBP-independent) might distinguish among these 3 individuals. Of all the assessed ratios, the 1,25(OH)D/24,25(OH)D ratio was the most informative, which had a value of 102 pg/ng in the individual with secondary hyperparathyroidism but lower values (41 and 20 pg/ng) in the other 2 individuals. These cases illustrate the value of the 1,25(OH)D/24,25(OH)D ratio to provide clinically relevant information about VitD status.
尽管临床指南建议检测血浆总25-羟基维生素D（25[OH]D）以评估维生素D（VitD）状态，但该指标未考虑VitD结合蛋白（VDBP）水平的个体间3倍差异。我们报告了3例血浆总25(OH)D水平为10.8至12.3 ng/mL（27 - 30.7 nmol/L）的个体。由于内分泌学会指南将VitD缺乏定义为25(OH)D≤20 ng/mL（50 nmol/L），这3例个体均会被判定为VitD缺乏。补充维生素D3后，25(OH)D升高至31.7至33.8 ng/mL（79.1 - 84.4 nmol/L）范围。患者1表现出继发性甲状旁腺功能亢进；补充维生素D3使甲状旁腺激素（PTH）降低了34%，而其他2例个体的PTH水平无临床显著变化。因此，25(OH)D水平无法区分出有继发性甲状旁腺功能亢进的1例患者和没有该病症的2例患者。我们因此探究VitD代谢物比率（独立于VDBP）是否能区分这3例个体。在所有评估的比率中，1,25(OH)D/24,25(OH)D比率最具信息量，继发性甲状旁腺功能亢进个体的该比率值为102 pg/ng，而其他2例个体的值较低（41和20 pg/ng）。这些病例说明了1,25(OH)D/24,25(OH)D比率在提供有关VitD状态的临床相关信息方面的价值。
