[Interest of bone alkaline phosphatase in hemodialysis patients].

Background: The renal osteodystrophy represent a major complication in hemodialysis.

Aim: To evaluate the value of plasma bone-alkaline phosphatase (bAP) in the diagnosis of the type of renal osteodystrophy among hemodialysis patients and to seek a possible correlation between the bAP, total alkaline phosphatases (tAP) and the intact parathormone (iPTH).

Methods: We studied 67 chronic hemodialysis patients. Plasma bAP was determined by immunoenzymatic technic. iPTH (1-84) was measured by electrochimiluminescence.

Results: We found that bAP levels were normal (10-20 ng/ml) in 17 patients, low (< 10 ng/ml) in 4 and high (> 20 ng/ml) in the 46 other patients. There is a good positive correlation between the plasmatic rate of bAP and the following parameters: the period of dialysis (R = 0.316, p = 0.009), plasmatic rate of tAP (r = 0.781, p < 10(-3)) and the rate of iPTH (r = 0.650, p < 10(-3)). There is a good positive correlation between the plasmatic rate of bAP and the rates of the tAP and of iPTH, the correlation between bAP and the iPTH being more significant. A rate of bAP higher than 20 ng/ml had a sensitivity of 93.5%, specificity of 63.3% in favour of a rate of iPTH >400 pg/ml and consequently of the biological diagnosis of hyperparathyroidism. In addition, 4 patients have a bAP <10 ng/ml with iPTH < 150 pg/ml evoking an adynamic osteopathy.

Conclusion: plasma bAP provides useful information about bone remodelling in hemodialysis patients.