Polycystic Kidney Disease (PKD)

Blood tests in PKD

How PKD is diagnosed

Complications of PKD

Questions to ask your nephrologist

• What is my total kidney volume: am I a rapid progressor?
• Am I eligible for tolvaptan (Jynarque) to slow cyst growth?
• Should I be screened for intracranial aneurysms?
• Should my children be tested?

Frequently Asked Questions

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

1. Chronic Kidney Disease. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK535404

References

Sources cited on this page. PubMed links open the original abstract.

1. Torres VE, Harris PC, Pirson Y. Autosomal dominant polycystic kidney disease. Lancet. 2007;369(9569):1287–1301. PMID 17582260 · doi:10.1016/S0140-6736(07)60601-1

How PKD damages the kidneys over decades

Polycystic kidney disease (PKD) is a genetic condition in which numerous fluid-filled cysts grow progressively within both kidneys. In autosomal dominant PKD (ADPKD) – the most common form, affecting 1 in 400–1000 people – a single inherited mutation in the PKD1 or PKD2 gene disrupts normal tubular cell signalling, causing abnormal fluid secretion and cyst expansion. The cysts compress surrounding normal kidney tissue, distort blood supply, and trigger inflammation and fibrosis.

Unlike most kidney diseases, PKD typically does not cause kidney failure until middle age. Average onset of end-stage renal disease (ESRD) is 54 years for PKD1 mutations and 74 years for PKD2, reflecting the slower cyst growth in PKD2. Total kidney volume (TKV) – measured by MRI – is the best predictor of disease progression rate. The Mayo Imaging Classification assigns patients to low-risk (type 1A–1B) or high-risk (types 1C–1E) based on TKV growth, informing the decision to start tolvaptan (see below).

Key blood and urine tests in PKD monitoring

There is no specific "PKD blood test" – monitoring focuses on detecting consequences of progressive kidney damage and excluding complications:

• eGFR and creatinine: The primary measure of kidney function. eGFR decline in PKD is often insidiously gradual for decades. Rate of eGFR decline (using the CKD-EPI equation) predicts time to dialysis.
• Urine albumin-to-creatinine ratio (ACR): Low-level proteinuria is common in PKD and correlates with disease severity. Macroscopic haematuria (blood in urine) occurs episodically as cysts rupture and usually resolves without treatment, but warrants prompt assessment to exclude urinary infection or cyst haemorrhage.
• Blood pressure monitoring: Hypertension is the most common complication of ADPKD, occurring in 60–80% of patients before significant eGFR decline. It is caused by increased renin secretion from compressed renal vasculature. Tight blood pressure control (target below 110/75 mmHg in younger patients, per the HALT-PKD trial) substantially slows GFR decline.
• Urine culture: Cyst infections are a serious complication. They present with fever, back pain, and elevated CRP – often without obvious urinary symptoms. Blood cultures and urine culture are essential as the causative organisms (usually E. coli) can be difficult to access inside cysts with standard antibiotics; fluoroquinolones (ciprofloxacin) penetrate cysts better than most alternatives.
• Haemoglobin: Unlike most CKD, ADPKD often causes polycythaemia (high haemoglobin) because cysts hypersecrete erythropoietin. In contrast, patients approaching ESRD develop anaemia as normal EPO production falls.

Tolvaptan – the first disease-modifying treatment

Tolvaptan (Jynarque) is a vasopressin V2 receptor antagonist that was approved specifically for ADPKD in 2018 (UK/EU). It reduces vasopressin-driven cyst fluid secretion, slowing TKV growth and preserving GFR. The landmark TEMPO 3:4 and REPRISE trials showed tolvaptan reduces the rate of eGFR decline by approximately 30% in rapidly progressing patients. It causes significant diuresis (up to 9 litres of urine per day initially) and carries a risk of serious liver toxicity requiring monthly liver function monitoring. NICE approved tolvaptan for adults at risk of rapidly progressing ADPKD (Mayo Class 1C–1E or equivalent eGFR decline).