Ureña P, Prieur P, Pétrover M
Service de Néphrologie, Clinique de l'Orangerie, Aubervilliers.
Presse Med. 1996 Oct 5;25(29):1320-5.
To evaluate the value of plasma bone-specific alkaline phosphatase (bAP) in the diagnosis and the prediction of the type of renal osteodystrophy in hemodialysis patients. To examine whether bAP correlated with the two classical biochemical markers of bone turnover in dialysis patients which are total alkaline phosphatases (tAP) and intact PTH (iPTH).
One hundred adult uremic patients undergoing regular hemodialysis therapy were included in the study. Plasma bAP was determined using a radioimmunometric assay. Intact PTH (1-84) was measured using a radioimmunometric assay, Allegro Intact PTH, Nichols Institute, CA, USA. Other laboratory tests including calcium, phosphorus, and tAP were performed by automated methods.
Based on previous biochemical and histological data obtained in the same type of patients, we arbitrarily divided plasma bAP levels in normal (10-20 ng/ml), low (< 10 ng/ml), and high (> 20 ng/ml). We found here that bAP levels were normal in 27 patients, high in 36, and low in 37. In the group with normal bAP, 8/27 patients had iPTH levels higher than 200 pg/ml, the other 19 patients had an iPTH within the normal range. In the 36 patients with high bAP, 10 showed markedly high iPTH and clinical signs of severe hyperparathyroidism leading to the indication of a surgical parathyroidectomy in 7 patients and i.v. calcitriol therapy in the other 3. However, 9 of these 36 patients had an iPTH lower than 200 pg/ml and 17 between 200-500 pg/ml. In the 37 patients with low bAP, iPTH levels were also low in 15 of them, but 12 patients had iPTH levels higher than 200 pg/ml. There was a good correlation between bAP, tAP, and iPTH. However, bAP correlated better with iPTH than tAP. A bAP > 20 ng/ml had a sensitivity of 56%, specificity of 92% and positive predictive value of 80% in the prediction of an PTH higher than > 400 pg/ml and therefore of the biological diagnosis of hyperparathyroidism. A bAP < 10 ng/ml had a sensitivity of 70%, specificity of 56% and a positive predictive value of 48% in predicting a normal-low iPTH (< 100 pg/ml).
In the absence of bone biopsy, plasma bAP self provides useful information about bone remodeling in hemodialysis patients. The combination of bAP and iPTH measurements further define the type of bone turnover. either elevated plasma bAP or iPTH alone are no always anonymous with secondary hyperparathyroidism.
评估血浆骨特异性碱性磷酸酶（bAP）在血液透析患者肾性骨营养不良诊断及类型预测中的价值。检测bAP是否与透析患者骨转换的两个经典生化标志物，即总碱性磷酸酶（tAP）和完整甲状旁腺激素（iPTH）相关。
本研究纳入100例接受定期血液透析治疗的成年尿毒症患者。采用放射免疫分析法测定血浆bAP。使用美国加利福尼亚州Nichols Institute的Allegro完整PTH放射免疫分析法测定完整PTH（1 - 84）。其他实验室检查，包括钙、磷和tAP，采用自动化方法进行。
根据之前在同一类患者中获得的生化和组织学数据，我们将血浆bAP水平随意分为正常（10 - 20 ng/ml）、低（< 10 ng/ml）和高（> 20 ng/ml）。我们发现，27例患者bAP水平正常，36例高，37例低。在bAP正常的组中，27例患者中有8例iPTH水平高于200 pg/ml，其他19例患者iPTH在正常范围内。在36例bAP高的患者中，10例显示iPTH明显升高且有严重甲状旁腺功能亢进的临床体征，其中7例患者需要进行甲状旁腺切除术，另外3例接受静脉注射骨化三醇治疗。然而，这36例患者中有9例iPTH低于200 pg/ml，17例在200 - 500 pg/ml之间。在37例bAP低的患者中，15例iPTH水平也低，但12例患者iPTH水平高于200 pg/ml。bAP、tAP和iPTH之间存在良好的相关性。然而，bAP与iPTH的相关性比与tAP的更好。bAP > 20 ng/ml在预测PTH高于400 pg/ml及因此甲状旁腺功能亢进的生物学诊断方面，敏感性为56%，特异性为92%，阳性预测值为80%。bAP < 10 ng/ml在预测正常 - 低iPTH（< 100 pg/ml）方面，敏感性为70%，特异性为56%，阳性预测值为48%。
在没有骨活检的情况下，血浆bAP自身可为血液透析患者的骨重塑提供有用信息。bAP和iPTH测量结果相结合可进一步明确骨转换类型。单独血浆bAP升高或iPTH升高并不总是意味着继发性甲状旁腺功能亢进。
