Severe hydronephrosis complicated with primary aldosteronism: a case report and review of the literature.

Background: Primary aldosteronism is characterized by high plasma aldosterone and low renin. The plasma aldosterone-to-renin ratio is recommended for screening. Severe hydronephrosis leads to renal parenchymal ischemia, resulting in increased renin secretion. Since nonsuppression of renin may cause a negative result in the aldosterone-to-renin ratio test, severe hydronephrosis and primary aldosteronism occurring simultaneously in a patient are challenging to diagnose.

Case presentation: A 54-year-old Chinese man of Han ethnicity was diagnosed with hypertension and severe hypokalemia (minimum 1.57 mmol/L) 13 years prior, and was also diagnosed with severe hydronephrosis due to congenital ureteral stenosis on the left side. His clinical features suggested primary aldosteronism, but the aldosterone-to-renin ratio result of the patient was negative every time he underwent the primary aldosteronism screening test. No further treatment for primary aldosteronism was performed, which led the patient to suffer from severe hypokalemia, such that he was taking 12-15 g/day potassium chloride orally to keep his blood potassium between 3.0 and 3.5 mmol/L (reference value, 3.5-5.5 mmol/L) for 13 years, and the patient needed to be hospitalized in the intensive care unit for rescue several times. At admission, although the aldosterone-to-renin ratio result of the patient was negative, we still did the saline stress test and captopril inhibition test, and the results showed that the plasma aldosterone level was not lower after the test than before the test. Adrenal enhanced computed tomography suggested an adenoma in the left adrenal gland, and the results of adrenal vein sampling suggested that the left side was the dominant side. Therefore, laparoscopic total resection of the left adrenal gland was performed, and 2 weeks later, the patient developed short-term renal function impairment and hyperkalemia, but his renal function and blood potassium returned to normal after treatment that included fluid rehydration. The patient's biochemical test results and clinical symptoms were completely normal after 1 year.

Conclusion: We suggest that for patients with a high suspicion of primary aldosteronism in the clinic, comprehensive analysis must be performed in combination with clinical characteristic assessments, such as severe hydronephrosis, if renin is within the normal range or if the aldosterone-to-renin ratio result is negative at screening and diagnostic tests, and adrenal vein sampling should be performed if necessary. It can help avoid misdiagnoses and contribute to the treatment of patients with severe hydronephrosis and primary aldosteronism.