131I-Iodo-cholesterol Scintigraphy for Primary Aldosteronism Lateralization in a Patient with Polycystic Kidney Disease

A 65-year-old male presented to our endocrinology clinic for further evaluation and treatment of primary aldosteronism (PA). Past medical history was notable for a kidney transplantation 17-years earlier due to polycystic kidney disease (PKD), and a diagnosis of PA, first established at age 52. As the patient had initially refused surgical management, no attempt at PA sub-type classification was pursued and he was medically managed with spironolactone. Over the years, blood-pressure control was poor and the patient became hypokalemic, despite large amounts of potassium supplements.

Due to the mass effect of the giant polycystic kidneys, the patient had been referred for a staged bilateral nephrectomy. During surgical planning, the option of concomitant adrenalectomy for PA if found to be unilateral, was reconsidered. The massive renal cysts grossly distorted normal retroperitoneal anatomy, making it impossible to identify the adrenal glands by either CT or MRI. Additionally, the complex anatomy made adrenal vein sampling both extremely difficult and risky.

In a multidisciplinary team meeting, the decision was made to perform an 131I-iodo-cholesterol scan (NP-59), which demonstrated a unilateral radiotracer accumulation in the left adrenal. Subsequently, a left adrenalectomy and nephrectomy was performed, resulting in rapid normalization of potassium levels and improvement of blood-pressure control. Spironolactone and doxazosin were discontinued. Pathology evaluation identified a 3cm adrenocortical adenoma.

Conclusion: 131I-Iodo-cholesterol scintigraphy is a useful modality for lateralization of PA and should not be disregarded. It could be used in selected cases, especially when adrenal venous sampling is contraindicated.