PotassiumNEW2026

Reninoma in an adolescent boy with negative selective renal vein sampling: a case report and review of the literature.

Zhang Lidan, Qiu Dongxu, Li Jia, Ma Xiaoyu et al. — Frontiers in endocrinology

Summary

This paper describes a rare case of a teenage boy with high blood pressure and dangerously low potassium levels caused by a small, benign kidney tumor called a reninoma. It highlights the significant challenges in diagnosing such tumors, which can lead to misdiagnosis and unnecessary medical procedures. The case emphasizes the critical importance of using various diagnostic tools to correctly identify the problem and ensure effective treatment.

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Key points

A rare kidney tumor called reninoma can cause high blood pressure and dangerously low potassium levels.
Diagnosing reninoma can be challenging, sometimes leading to misdiagnosis and unnecessary surgeries.
Using multiple diagnostic methods, including specialized imaging, is crucial for accurate identification.
Successful removal of the tumor can resolve both high blood pressure and low potassium without medication.

What the study looked at

This paper didn't ask a broad research question but rather presented a detailed account of a specific patient's journey to highlight the diagnostic challenges of a rare condition. It aimed to illustrate how a rare kidney tumor, a reninoma, can cause severe high blood pressure and low potassium, and how difficult it can be to correctly identify. This was a case report focusing on a 13-year-old boy who suffered from high blood pressure and low potassium for two years. The study documented his initial misdiagnosis, the various tests performed (including blood tests, CT scans, and specialized ultrasound), and the eventual surgical removal of the tumor. The boy's condition, initially misdiagnosed, was ultimately identified as a small reninoma in his kidney. The report found that standard tests sometimes failed to pinpoint the tumor, but a specialized ultrasound helped. After the tumor was removed, his blood pressure and potassium levels returned to normal without any medication, confirming the tumor was the cause. The case suggests that a combination of different diagnostic tools is essential for accurate diagnosis of such rare conditions.

Dietary takeaway

This case highlights that extremely low potassium levels, especially when combined with high blood pressure, can sometimes signal an underlying medical condition beyond just diet. While increasing potassium-rich foods like fruits and vegetables is generally healthy, persistent low potassium warrants medical investigation. Remember, this is a single case report, and its findings are not definitive for everyone.

Abstract

Juxtaglomerular cell tumor (reninoma) is a rare benign renal neoplasm causing secondary hypertension via autonomous renin over-secretion, which is extremely rare in children and adolescents. Here we report a 13-year-old boy with a two-year misdiagnosis of resistant hypokalemic hypertension, who underwent unnecessary left adrenalectomy based on ambiguous adrenal computed tomography (CT). Biochemical tests revealed hyperreninemic hyperaldosteronism with normal aldosterone-to-renin ratio. Renal artery CT identified a tiny low-density lesion in the upper pole of the left kidney, while contrast-enhanced ultrasound (CEUS) clearly displayed characteristic hypoperfusion of the mass. Selective renal vein sampling (SRVS) failed to demonstrate a lateralized renin gradient, a finding consistent with the known low sensitivity of this test for small juxtaglomerular cell tumors (JGCT). Laparoscopic nephron-sparing tumorectomy was performed, and histopathological and clinical features together supported the diagnosis of reninoma. Blood pressure and serum electrolytes normalized postoperatively without antihypertensive or potassium supplementation, with complete quantitative biochemical and imaging surveillance confirming stable remission over the 3-year follow-up. This case highlights that CEUS acts as a radiation-free auxiliary localization modality for suspected pediatric reninoma and provides complementary functional information when SRVS yields false-negative results; definitive diagnosis requires integrated assessment of clinical manifestations, biochemical markers, multimodal imaging, and pathological findings rather than relying on a single imaging technique. Clinicians should raise vigilance of reninoma in children with refractory hypokalemic hypertension to avoid misdiagnosis and unnecessary adrenal surgery.

View on PubMed →DOI: 10.3389/fendo.2026.1942257