PERITONEAL CLEARANCE OF THE INTACT PARATHYROID-HORMONE IN CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS

We studied the peritoneal elimination and clearance of intact parathyr oid hormone in 34 patients diagnosed as suffering end stage renal dise ase on treatment with continuous ambulatory peritoneal dialysis: 20 ma les and 14 females, average age 60.6 +/- 9.9 years (35-75), average ti me on treatment 22.6 +/- 14.5 months (3-54), 17 anuric patients, 17 wi th residual renal function; 22 patients were being treated with with 8 L per day and 12 with 6 L per day. The concentration of intact parath yroid hormone (I-PTH) in the blood and in the peritoneal liquid for 24 hours was determined by means of immunoradiometry and the peritoneal clearance was calculated. The results obtained were as follows. serum I-PTH 232.0 +/- 357.9 (103.6) pg/ml, I-PTH in peritoneal liquid 34.44 +/- 27.54 (26.72) pg/ml, I-PTH in pe ritoneal liquid in 24 hours 0.26 +/- 0.15 (0.22) mcg/24 h, peritoneal clearance I-PTH 2.35 +/- 2.43 (1. 49) ml/min (values expressed as average +/- DE [median]). There is a p ositive linear correlation between the serum I-PTH and the I-PTH drain ed off per millilitre and in 24 hours (r = 0.72 and r = 0.70 respectiv ely). There also appeared a close negative correlation between the ser um I-PTH and its peritoneal clearance, described by means of a potenti al regresion model (r = -0.91). We concluded that: I) The peritoneal e limination of intact parathyroid hormone increases (although very slig htly) the higher the blood values. 2) The peritoneal clearance of I-PT H depends mainly on its blood levels. 3) The I-PTH clearance curve sug gests a peritoneal saturation mechanism.