CT imaging of abdomen and pelvis
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CT imaging of abdomen and pelvis - 2
A 50-year-old male presents to establish nephrology care. He was definitively diagnosed with polycystic kidney disease about 10 years previously. He has a positive family history among his paternal relatives.
He denies urinary tract infections, gross hematuria, or past nephrolithiasis. He has no urgency or incomplete emptying with urination. He does have chronic abdominal fullness and occasional dyspepsia related to his enlarged cystic kidneys. He denies heart disease and has no family history of cerebral hemorrhage or aneurysm. He is not taking any medications and has only sporadically seen a doctor in the past.
His blood pressure is 152/82. Physical examination is remarkable for large, palpable kidneys. There is no evidence of hernia. There is no lower extremity edema. His serum creatinine is 2.2 mg/dL, potassium is 3.8 mEq/L, and hemoglobin is 14 g/dL. Urine shows 30 protein on dipstick. CT imaging of abdomen and pelvis had been performed and representative images are shown:
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This patient has autosomal dominant polycystic kidney disease. He has stage 3b chronic kidney disease with large cyst burden in kidneys that measure over 30 cm bilaterally. His blood pressure is currently not adequately controlled.
Polycystic kidney disease (PKD) is characterized by autosomal dominant inheritance. Over 300,000 Americans are affected and PKD causes at least 5% of ESRD cases. Decline in renal function is related to continued cyst growth and associated destruction of functioning nephrons.
Patients with PKD tend to have over-activity of the renal renin-angiotensin system. Inhibition of this system is indicated and is the cornerstone of anti-hypertensive therapy in such patients. Recent studies have examined use of ACE inhibitors alone and in combination with angiotensin receptor blockers. In the recent HALT studies, combination treatment did not prove superior to ACE inhibitor alone in a composite endpoint that included preventing death or eGFR decline in patients with late PKD (eGFR less than 60ml/min).
Cyst growth in PKD is known in part to be mediated by activity of anti-diuretic hormone (vasopressin). Some specialists recommend judicious water intake in PKD to lower vasopressin levels in the hope of limiting cyst growth. In the past few years, the TEMPO study has examined the use of tolvaptan, a vasopressin 2 receptor antagonist, in limiting cyst growth and progression of PKD. Tolvaptan use in those with creatinine clearance over 60mL/min did lead to slower growth in total kidney volume and slower decline in kidney function over 3 years. While this agent is promising in PKD patients, it is not FDA approved for PKD patients in the U.S. (The study did lead to a FDA warning about potential associated liver injury with this agent.)
Other studies have investigated the use of mTOR inhibitors such as sirolimus and everolimus. Some of those studies did show improvement in total kidney volume with these agents while others have not. Side effects of these agents led to high dropout rates. Somatostatin analogues and statin therapy have also been studied in CKD. Statins in particular may have beneficial effects when started early with limited side effect profile. However, further longer-term studies are needed.
PKD patients are known to have higher incidence of cerebral aneurysms. Screening for aneurysms in PKD is currently recommended for those at “high risk,” including those with a family history of aneurysm, certain occupations, with warning symptoms, and those undergoing surgery with potential for hypertension/hemodynamic shifts.
Our patient with late stage PKD was started on ACE inhibitor therapy to control hypertension and educated on the importance of routine nephrology follow up.
Braun WE, Schold JD, Stephany B, et al. Low-dose rapamycin (sirolimus) effects in autosomal dominant polycystic kidney disease: an open-label randomized controlled pilot study. Clin J Am Soc Nephrol 2014;9:881-888
Torres VE, Abebe KZ, Chapman AB, et al; HALT-PKD Trial Investigators. Angiotensin blockade in late autosomal dominant polycystic kidney disease. N Engl J Med 2014;371:2267-2276.
Torres VE, Chapman AB, Devuyst O, et al; TEMPO 3:4 Trial Investigators. Tolvaptan in patients with autosomal dominant polycystic kidney disease. N Engl J Med 2012;367:2407-2418.
This case was prepared by Kevin T. Harley, MD, Assistant Clinical Professor of Medicine, Division of Nephrology & Hypertension, at the University of California in Irvine.