RESUMEN
To evaluate the effect of an acute oral protein load (OPL) on urinary albumin excretion (UAE) in uninephrectomized subjects with a negative Albustix test, in relation to the time since nephrectomy, the UAE was determined by a double-antibody 125I radioimmunoassay in 3-hour urine collections before and after 150 g OPL under conditions of moderate physical activity in 18 subjects who underwent unilateral nephrectomy more than 10 years (346.5 +/- 178.60 months) before evaluation and had a mean basal creatinine clearance (CCr) of 45.3 +/- 14 ml/min (group 1), in 21 subjects who underwent unilateral nephrectomy less than 10 years (31.5 +/- 28 months) before evaluation and had a mean basal CCr of 76.0 +/- 22 ml/min (group 2), and in 16 normal volunteers (controls) with a mean basal CCr of 103.1 +/- 12 ml/min. The UAE was higher in group 1 as compared with either group 2 or controls at both basal state (90.8 +/- 65, 19.6 +/- 17, and 11.0 +/- 5 micrograms/min/100 CCr for groups 1 and 2 and controls, respectively; p < 0.001) and after OPL (92.0 +/- 65, 43.6 +/- 24, and 12.0 +/- 5 micrograms/min/100 CCr for groups 1 and 2 and controls, respectively; p < 0.001). However, the increase in UAE following OPL was significant (p < 0.001) only in group 2 patients. In all patients, the basal UAE was negatively correlated with basal CCr (r = 0.63; p < 0.001) and positively correlated with the time since nephrectomy (r = 0.73; p < 0.001) and with both systolic (r = 0.57; p < 0.001) and diastolic blood pressures (r = 0.69; p < 0.001). CCr calculated using 3-hour urine collections increased more in controls (11.2 +/- 44.2%) than in patient groups 1 (1.6 +/- 0.89) and 2 (7.7 +/- 3.7%; p < 0.001). Basal CCr calculated using 24-hour urine collections the day before the test was negatively correlated with the time since nephrectomy in group 1 (r = -0.69; p < 0.001) and positively correlated with the time since nephrectomy in group 2 (r = 0.89; p < 0.001). Multiple regression analysis revealed that the relationship between CCr and duration of uninephric state was independent of age or systolic and diastolic blood pressures in both patient groups. These results suggest that UAE increase significantly after an OPL in subjects who have been nephrectomized less than 10 years before the study and have basal CCr values higher than 50% of normal.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Albuminuria/etiología , Proteínas en la Dieta/administración & dosificación , Nefrectomía/efectos adversos , Administración Oral , Adulto , Anciano , Biomarcadores , Creatinina/metabolismo , Femenino , Tasa de Filtración Glomerular , Humanos , Fallo Renal Crónico/etiología , Masculino , Persona de Mediana Edad , Factores de Riesgo , Factores de TiempoRESUMEN
The effect of an intravenous calcium gluconate load (10 mg/kg over 5 min) on plasma ionized calcium concentration, parathyroid hormone (PTH), and the rate of urinary excretion of calcium, sodium, and nephrogenous cyclic adenosine monophosphate (NcAMP) was examined in 26 patients with essential hypertension and 27 age- and sex-matched normotensive subjects. Prior to calcium administration hypertensives had lower plasma ionized calcium concentration (P < .01) and higher PTH levels (P < .001) and excreted more calcium (P < .05) and NcAMP (P < .001) in the urine compared to normotensives. Following calcium infusion, plasma ionized calcium did not differ significantly between the two groups, but PTH levels remained higher in the hypertensive subjects at both 60 min (P < .001), and at 120 min (P = .02) post-load. Post-load values for both urinary calcium excretion and urinary sodium excretion were significantly higher in the hypertensive subjects than in the control group. Both before and after calcium infusion, urinary calcium excretion was positively correlated with urinary sodium excretion in each of the two groups, but for the same level of sodium excretion, hypertensives excreted more calcium in the urine, compared to normotensives, both before (P < .05) and after calcium infusion (P < .001). A positive correlation between basal plasma renin activity (PRA) values and plasma ionized calcium values obtained before (r = 0.42, P = .03) or at 60 min (r = 0.41, P = .03) and 120 min (r = 0.42, P = .03) after calcium infusion existed only in the hypertensive subject group. Post-load urinary sodium excretion values were negatively correlated to basal PRA values in both groups (r = -0.55, P < .01 and r = -0.58, P < .01 for hypertensives and normotensives, respectively), but a similar negative correlation between post-load urinary calcium excretion values and basal PRA values existed only in the hypertensive subject group (r = -0.50, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Calcio/farmacología , Calcio/orina , Hipertensión/fisiopatología , Natriuresis/efectos de los fármacos , Glándulas Paratiroides/efectos de los fármacos , Adulto , Femenino , Humanos , Hipertensión/sangre , Hipertensión/orina , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Concentración Osmolar , Glándulas Paratiroides/fisiopatología , Hormona Paratiroidea/sangre , Valores de ReferenciaRESUMEN
To evaluate the role of calcium and the parathyroid gland in the pathophysiology of essential hypertension, creatinine clearance, urinary excretion of sodium, calcium and nephrogenous cyclic adenosine monophosphate (NcAMP) and serum parathyroid hormone (PTH) levels were measured in 25 newly diagnosed essentially hypertensive patients before institution of any treatment and in 25 age- and sex-matched normal volunteers. While no significant differences in creatinine clearance, serum total calcium levels or 24-hour sodium excretion existed between the two groups, hypertensives had a higher mean (+/- SD) 24-hour calcium excretion rate (199.0 +/- 44.7 vs. 152.8 +/- 33.6 mg, p less than 0.001), a higher mean NcAMP excretion rate (2.54 +/- 0.8 vs. 1.87 +/- 0.5 nmol/100 ml glomerular filtrate, p less than 0.001) and a higher mean serum PTH concentration (1.87 +/- 0.6 vs. 1.53 +/- 0.4 ng/ml, p less than 0.001) than the normotensives. A significant positive correlation existed between calcium and sodium excretion in both hypertensives (r = 0.66, p less than 0.001)) and normotensives (r = 0.67, p less than 0.001), but given the same levels of creatinine clearance and sodium excretion, hypertensives excreted more calcium than normotensives (p less than 0.001)). In both hypertensives and normotensives, serum PTH levels were positively correlated with NcAMP excretion (r = 0.42, p less than 0.05, and r = 0.41, p less than 0.05, respectively) and the ratio of urinary sodium to urinary calcium excretion (r = 0.59, p less than 0.001, and r = 0.75, p less than 0.001), respectively). The above results suggest that in essential hypertension, increased activity of parathyroid glands may occur as a consequence of increased urinary calcium losses which are presumably due to an intrinsic defect in renal calcium handling.