What are the most frequent complications of ADPKD?
• Hypertension: The majority of patients with ADPKD present with abnormal blood pressure levels. Studies have shown that hypertension is diagnosed 15 years earlier in ADPKD patients compared with those with essential hypertension. Indeed, the prevalence of hypertension reaches 50% in patients aged 20 to 30 years, representing the initial presentation for 30% of ADPKD patients, but increases to 100% of those with ESKD.
• The pathogenesis of hypertension in ADPKD is complex, and the most plausible hypotheses include activation of the renin-angiotensin-aldosterone system, cyst expansion, intrarenal ischemia, and decreased expression levels of polycystin-1 and 2, and nitric oxide (NO) availability. Importantly, uncontrolled blood pressure is associated with increased mortality rates from valvular heart disease and aneurysms, increases the risk of proteinuria and hematuria, and increases speed of decline of kidney function. Therefore earlier detection and treatment of hypertension and more rigorous blood pressure control are important on these patients.
• Pain: Approximately 60% of patients with ADPKD suffer from pain, the most common symptom reported by adults with ADPKD. Pain is most commonly located in the flank, back, and abdomen and is primarily attributed to cystic compression of the kidney capsule and parenchyma, but it can also be caused by hemorrhage into a cyst, cyst rupture, or infection. Importantly, kidney stones or tumor should be always ruled out. Acute causes of kidney pain include renal hemorrhage, passage of stones, and urinary tract infections (UTIs). Cyst hemorrhages often resolve within a week, but if it is prolonged or if the initial episode occurs after the age of 50 years, screening to exclude neoplasm should be done. Although most patients with hepatic cysts are asymptomatic, cystic enlargement of the liver may also cause mechanical back pain.
• Nephrolithiasis: Kidney stones occur in 20% to 36% of patients with ADPKD. The most common types of stones are composed of uric acid or calcium oxalate. Metabolic factors such as low urine citrate and urine pH, and decreased ammonia excretion may predispose to stone formation, yet urinary stasis due to distorted kidney anatomy may also prompt stone formation. Abdominal CT before and following contrast enhancement is important to detect renal calculi. Stones may be missed if only a contrast-enhanced CT is performed.
• Urinary infections: In ADPKD, UTIs are more frequent in women than in men, as in the general population. UTIs are usually caused by gram-negative enteric bacteria (Enterobacteriaceae) . Although CT and MRI can detect cyst complications and provide anatomic definition, none of these findings are specific for infection. Alternatively, nuclear imaging with 67 Ga- or 111 In-labeled leukocyte scans may be used, but false negative and false positive may occur. An 18-F-fluorodeoxyglucose PET scan is a promising agent for detection of infected cysts. However, its efficacy for diagnosing UTI is limited. When a kidney cyst infection is suspected, delayed images should be obtained. Finally, in the event that the clinical setting and imaging are suggestive of infection, but blood and urine cultures are negative, cyst aspiration should be considered.
• ESKD: ADPKD is the leading inheritable cause of ESKD, with 45% of patients with ADPKD developing ESKD by 60 years of age. Men tend to progress faster than women, which may be partly attributed to a greater prevalence and severity of hypertension. There is a strong relationship between kidney volume growth and glomerular filtration rate (GFR) decline.
