Carnevale Vincenzo, Dionisi Simona, Nofroni Italo, Romagnoli Elisabetta, Paglia Federica, De Geronimo Simona, Pepe Jessica, Clemente Giovanni, Tonnarini Gianfranco, Minisola Salvatore
Department of Internal Medicine, Casa Sollievo della Sofferenza Hospital, IRCCS, Viale dei Cappuccini, San Giovanni Rotondo, FG, Italy.
Clin Chem. 2004 Mar;50(3):626-31. doi: 10.1373/clinchem.2003.026328. Epub 2004 Jan 12.
A new commercially available (so-called second-generation) IRMA for parathyroid hormone (PTH) separately detects intact PTH and its N-truncated fragments; however, no studies have compared the first- and second-generation IRMAs for PTH in patients with primary hyperparathyroidism (PHPT) to assess their respective diagnostic accuracies.
We concomitantly investigated 39 postmenopausal patients with PHPT and a control group of 70 healthy postmenopausal women matched for age, renal function, and vitamin D status. In all individuals, PTH was measured with a classic IRMA (PTH-S; DiaSorin Inc.), which uses antibodies directed against epitopes 1-34 and 39-84, and a new method (Scantibodies Laboratory. Inc.), which uses antibodies against epitopes 1-4 and 39-84 (PTH-W) and epitopes 7-34 and 39-84 (PTH-T). We also assayed serum PTH in 10 PHPT patients every 24 h for 5 days after successful surgery.
The different assays gave serum PTH values that were >2 SD higher than values for the control population in 59% (PTH-S), 77% (PTH-W), and 82% (PTH-T) of patients with PHPT. However, ROC curve analysis showed no significant differences among the three PTH assays, demonstrating overlapping diagnostic sensitivities. In PHPT patients, the correlation among the assays was highly significant (r = 0.91-0.92; P <0.001). The ratio PTH-W:PTH-T x 100 showed a gaussian distribution in both PHPT patients and controls, whose mean (SD) values [63.4 (13.3)% vs 64.5 (9.5)%, respectively] did not differ significantly. After parathyroidectomy, the mean percentages of variation in PTH detected with all of the assays were quite similar.
The distribution of the PTH-W:PTH-T ratio in patients and controls suggests that PHPT does not markedly influence the rate at which biologically inactive fragments are generated by central or peripheral cleavage of PTH. The similar postoperative curves seem to contradict the hypothesized effect of acute hypocalcemia in modulating the central secretion of hormonal fragments. Our results indicate that the three investigated assays have similar diagnostic sensitivities in PHPT.
一种新的可商购的（所谓第二代）甲状旁腺激素（PTH）免疫放射分析（IRMA）可分别检测完整PTH及其N端截短片段；然而，尚无研究比较第一代和第二代PTH免疫放射分析在原发性甲状旁腺功能亢进症（PHPT）患者中的诊断准确性。
我们同时研究了39例绝经后PHPT患者以及70例年龄、肾功能和维生素D状态相匹配的绝经后健康女性组成的对照组。在所有个体中，使用针对表位1-34和39-84的抗体的经典免疫放射分析（PTH-S；DiaSorin公司）以及使用针对表位1-4和39-84（PTH-W）和表位7-34和39-84（PTH-T）的抗体的新方法（Scantibodies实验室公司）测量PTH。我们还在10例PHPT患者成功手术后的5天内，每24小时检测一次血清PTH。
不同检测方法得出的血清PTH值在59%（PTH-S）、77%（PTH-W）和82%（PTH-T）的PHPT患者中比对照组人群的值高出>2个标准差。然而，ROC曲线分析显示三种PTH检测方法之间无显著差异，表明诊断敏感性重叠。在PHPT患者中，各检测方法之间的相关性非常显著（r = 0.91 - 0.92；P <0.001）。PTH-W:PTH-T×100的比值在PHPT患者和对照组中均呈高斯分布，其均值（标准差）分别为[63.4（13.3）%对64.5（9.5）%]，无显著差异。甲状旁腺切除术后，所有检测方法检测到的PTH变化的平均百分比非常相似。
患者和对照组中PTH-W:PTH-T比值的分布表明，PHPT对PTH通过中央或外周裂解产生无生物学活性片段的速率无明显影响。相似的术后曲线似乎与急性低钙血症调节激素片段中央分泌的假设效应相矛盾。我们的结果表明，所研究的三种检测方法在PHPT中具有相似的诊断敏感性。
