ABSTRACT
Twenty-four hour urine and spot urine samples from 29 patients with metabolic acidosis were collected for evaluation of urine ammonium in relation to urine anion gap, urine osmolal gap (OG) and modified urine osmolal gap (MOG). Their underlying diseases included SLE in 8, RTA in 7, CRF in 6, RPGN in 2 (one with SLE), Lowe syndrome in 2, on acetazolamide in 2, gastroenteritis in 2, and CAH in one. Twenty-three patients had normal serum anion gap (< 14 mmol/L). Their mean CO2 was 13.77 (9.4-17.9) mmol/L, net acid excretion (NAE) was 33.18 +/- 35.36 mmol/24 hour, NH+4 excretion was 29.16 +/- 31.97 mmol/24 hour. Neither the 24-hour urine nor spot urine anion gap correlated with corresponding urine NH+4 with or without adding urine HCO-3 in the calculation. Spot urine NH+4 correlated well with urine OG (r2 = 0.82, p < 0.001) and less with MOG (r2 = 0.339, p < 0.006). The urine osmolality was well correlated with the sum of 2 (Na+ + K+ + NH+4) + urea for both spot (r2 = 0.990, p < 0.001) and 24 hour urine (r2 = 0.907, p < 0.001) collection. Twenty-four hour urine NH+4 did not correlate with the OG or the MOG. There was no correlation between spot urine NH4/Cr ratio and 24 hour urine NH4/Cr ratio (r2 = 0.243, p = 0.53) nor between spot NAE/Cr ratio and 24 hour urine NAE/Cr ratio (r2 = 0.380, p = 0.014). Therefore in the presence of low urine NH+4 (< 100 mmol/L), urine osmolal gap may be used to determine urine NH+4 indirectly with good correlation. Twenty-four hour urine collection is still necessary to assess renal acidification.
Subject(s)
Acid-Base Equilibrium , Acidosis/urine , Adolescent , Child , Child, Preschool , Female , Humans , Infant , Male , Osmolar Concentration , Quaternary Ammonium Compounds/urineABSTRACT
Antecedentes: La encefalopatía hepática (EH) es un síndrome neuropsicológico de origen multifactorial. Desde hace cuatro décadas se han propuesto algunas teorías para explicar la fisiopatogenia, por lo que se han utilizado múltiples tratamiento de acuerdo con los postulados de dichas teorías. Objetivo: Exponer y analizar de forma actualizada las teorías más importantes implicadas en la fisiopatogenia de la EH (amonio, mercaptanos, ácidos grasos de cadena corta, falsos neurotransmisores, ácido gamma aminobutírico y benzoadiacepinas endógenas). Asimismo, hacer énfasis en la eficacia terapéutica de los diferentes tratamiento a los cuales dichas teorías han dado origén. Métodos: Se realizó una intensa revisión bibliogáfica utilizando la base de datos Med-Line y Current Contents, poniendo especial énfasis en los artículos terapéuticos publicados en los últimos diez años. Resultados: De todas las teorías propuestas, la amoniacal, actualmente "resucitada", parece explicar mejor la fisiopatología de la EH, por lo que los agentes terapéuticos con mayor efectividad son aquellos que reducen su generación y su absorción en intestino, y que aumentan su eliminación renal. Los autores proponen mecanismos de acción del amonio y de la serotonina a nivel de los neurotransmisores, particularmente en la neurotransmisión glutamatérgica excitatoria. Conclusiones: Parece ser que el amonio juega un papel preponderante en la fisiopatogenia de la EH. Probablemente existan otros agentes actualmente poco definidos. Los efectos sobre la neurotransmisión quedan por dilucidarse
Subject(s)
Humans , Liver Cirrhosis/complications , Liver Cirrhosis/physiopathology , Hepatic Encephalopathy/physiopathology , Hepatic Encephalopathy/therapy , gamma-Aminobutyric Acid , Neurotransmitter Agents/physiology , Quaternary Ammonium Compounds/blood , Quaternary Ammonium Compounds/cerebrospinal fluid , Quaternary Ammonium Compounds/urineABSTRACT
To study the mechanism of hypercalciuria in metabolic acidosis, ammonium chloride loading (long) test was performed in 68 stone formers and 50 controls. Administration of ammonium chloride in both stone formers and controls produced a significant increase in urinary volume, ammonium and calcium excretions, no change in plasma calcium and creatinine clearance and significant decrease in plasma bicarbonate. However, on the third day of ammonium chloride loading test, urinary ammonium excretion and plasma bicarbonate levels were significantly lower while urinary calcium excretion was significantly greater in stone formers than in controls. Thus calciuresis could be correlated with the degree of metabolic acidosis but not with the rate of urinary ammonium excretion.