Effect of Mineralocorticoid on Serum Potassium Regulation and Urine Ammonium Excretion in Chronic Renal Patients / 대한신장학회잡지

Mineralocorticoids influences on acid-base homeostasis by the regulation of urine acidification. But its mechanism of acion is not well known in human. This study compared the acid-base status and the indices of urine acidification before and after mineralocorticoid administration in human, and analyzed the effect of mineralocorticoids on human acid-base homeostasis. We administered 9a-fludrocortisone in 6 chronic renal failure patients and 6 normal controls 0.5mg daily for 7 days. The results were as following: 1) After administration of 9a-fludrocortisone in patients group, serum aldosterone level changed from 120.2+/-71.0pg/mL to 44.8+/-32.2pg/mL(mean+/-SD, p< 0.05). Serum HCO- level was not changed. Urine ammonium excretion was incresed from 24.6+/-12.3 mmol/day to 43.7+/-19.0 (p<0.05), but there were no change in urine pH and urine anion gap, Serum potassium level decreased from 5.5+/-0.7mBq/L to 4.1+/-0.5mEq/L (p<0.05), and TTKG increased from 3.9 to 8.9(p<0.05). 2) After administration of 9a-fludrocortisone in control group, serum aldosterone level changed from 99.7+/-44.5pg/mL to 25.1+/-3 mL(p<0.05). Serum HCO- level was not changed. Urine ammonium excretion was incresed from 44.3+/-21.6mmoVday to 76.3+/-19.6(p<0.05), but there were no change in urine pH and urine anion gap. Serum potassium level decreased from 4.8+/-0.5mEq/L to 3.9+/-0.2mHq/L(p< 0.05), but there was no change in TTKG. 3) No patient or control showed any discomfort after 9-fludrocortisone administration, and there was no elevation in diastolic blood pressure, increase in body weight, electrolyte abnormality. In summary, after 9alpha-fludrocortisane administration, urinary ammonium excretion increased in both patients and control group, and this phenomenon occured with correction of hyperkalemia without urine pH change. This result implies urinary ammonium excretion increase by mineralocorticoid. In human increase in renal distal acidification by mineralocorticoid is due to increase in renal ammoniagenesis rather than stimulation on proton excretion.

Clinical Usefulness of Transtubular Potassium Gradient(TTKG) and Urine Ammonium in Differential Diagnosis of Hypokalemia / 대한신장학회잡지

Hypokalemia is frequently encountered in clinical medicine, the cause of which can usually be determined from the history such as with diuretic use, vomiting, or diarrhea. And measurement of urinary indices such as excretory rate of K+, random urine K+ and fractional excretion of K+ and assessment of acid-base balance have been applied to the pathophysiologic diagnosis without fruitful success. To investigate the clinical usefulness of TTKG and urine ammonium in differential diagnosis of hypokalemia, we evaluated serum electrolytes and osmolality, random(spot) urine electrolytes, osmolality and ammonium, total CO2, UNa/K, plasma aldosterone and TTKG in 7 patients with diarrhea, 6 patients with vomiting, 7 patients with 3 primary hyperaldosteronism and 4 renovascular hypertension, 6 patients with diuretic uses. With the comparison to 7 overnight fasting and acid-loaded normal controls, we obtained the following results. 1) Random measurement of the urine potassium concentration did not accurately reflect potassium wasting if the urine became concentrated. So clinical usefulness of random urine potassium concentration was limited. 2) UNa/K was useful in the diagnosis of mineralocorticoid excess such as primary hyperaldosteronism and renovascular hypertension rather than the other causes of hypokalemia. 3) TTKG was very useful in differential diagnosis of hypokalemia between potassium losses through the gastrointestinal tract (below 2) and kidney (above 10), and it had a good correlation with the aldosterone activity in the hypokalemic patients due to renal loss. 4) Random urine ammonium was a useful index in differential diagnosis of hypokalemia with acid-base disturbances. In conclusion, TTKG and random urine ammonium were very useful indices in differential diagnosis of the causes of hypokalemia.

Correlation of Urine Ammonium with Urine Osmolal Gap in High Anion Gap Matabolic Acidosis: Comparison to Urine Anion Gap / 대한내과학회지

OBJECTIVES: Urine anion gap(UAG) and urine osmolal gap(UOG) were proposed as indirect measures of urine ammonium(NF4+). While the former is known to have its usefulness limited to hyperchloremic metabolic acidosis, the latter is reported to have its correlation with urine NE4+ in ketoacidosis. This study was undertaken to evaluate the correlation of urine NH with IJOG in high anion gap metabolic acidosis(AGMA) and to compare it with UAG. METHODS: We measured urine NH' by enzymatic determination, UOG(=0.5 X [urine osmolality-{2 X (Na++K+)+urea+glucose)]), and UAG(=Na++K+-Cl-) in 18 patients(serum AG=24.4+/-1.6mmol/L ) with AGMA. RESULTS: When they were grouped into those with acute disorders(n=11) and those with chronic disorder(n=7), urine Nk4+ concentration was higher (p40mmol/d) had the UOG>40mmol/L. CONCLUSION: In contrast to the UAG, the UOG has a significant correlation with urine NH4+ in AGMA.