A hidden nonfunctioning kidney in autosomal dominant polycystic kidney disease

A 55-year-old woman with autosomal dominant polycystic kidney disease (ADPKD) visited our clinic to discuss treatment with tolvaptan. She had hypertension managed with an angiotensin receptor blocker and no other symptoms related to ADPKD. A non-enhanced computed tomography (NECT) scan from another hospital indicated a total kidney volume (TKV) of 1,150 mL (height-adjusted TKV of 745 mL), measured using the stereology method, corresponding to Mayo imaging classification 1C (Fig. 1A). Her estimated glomerular filtration rate (eGFR) was 44 mL/min/1.73 m². She reported no family history of early-onset end-stage kidney disease, and genetic testing had not been conducted. Additionally, she had no history of hypertension or urologic symptoms before age of 35 years.

Figure 1. Imaging findings of a hidden nonfunctioning kidney in autosomal dominant polycystic kidney disease.

(A) A non-enhanced computed tomography performed 1 year earlier shows multiple bilateral renal cysts consistent with autosomal dominant polycystic kidney disease. (B) A magnetic resonance imaging reveals hydronephrosis, which can be clearly distinguished from renal cysts. (C) A diuretic renal scan using technetium-99m diethylenetriamine pentaacetic acid indicates no residual function in the left kidney.

Despite the lack of typical high-risk features, her relatively low eGFR for her age suggested a rapidly progressive form of the disease. Consequently, tolvaptan therapy was initiated to slow the progression of ADPKD. One year later, follow-up magnetic resonance imaging (MRI) for TKV measurement showed left-sided hydronephrosis due to ureteropelvic junction (UPJ) obstruction, which had not been identified on the initial NECT (Fig. 1B). A diuretic renal scintigraphy demonstrated no measurable function in the left kidney (Fig. 1C). Given the absence of established guidelines or evidence supporting tolvaptan use in ADPKD patients with a single functioning kidney, the medication was discontinued. Over the next three years following discontinuation, her eGFR declined at a rate of −6.34 mL/min/year.

MRI is the preferred method for assessing TKV in ADPKD patients; however, computed tomography is often used in routine practice due to its availability. Clinicians should be aware that important structural abnormalities, such as hydronephrosis, may be missed when using NECT. In cases where UPJ obstruction is suspected in ADPKD, renal scintigraphy can assess split renal function, as it did in this case, revealing complete functional loss of the affected kidney and prompting a change in treatment strategy.