Monday, December 19, 2016

Autosomal dominant polycystic kidney disease

Here are some key points from a recent BMJ review:

What is it?

It is an inherited condition characterized by pathologic development of multiple renal cysts leading to enlargement and dysfunction.

What are the genetics?

Classic autosomal dominance. However, some patients will not have a family history, as 6-8% of cases represent de novo mutations. The mutation involves one of two identified genes.

The variable clinical spectrum is not fully explained.

This is in part due to there being two separate gene mutations. However, within a given mutation there is considerable variation in severity.

There is a wide array of renal manifestations.

Urinary concentrating impairment is an early manifestation. Episodic hematuria and cyst hemorrhage may occur and generally resolve in a matter of days. Cyst infection is complicated and requires prolonged antibiotic treatment with a lipid permeable agent. Hypertension is common and may be the initial presenting clinical feature. The median age of onset of ESRD is 55 but is quite variable.

What are the extrarenal manifestations?

Polycystic liver disease is seen in 80% of adults. Biliary tract compression, cholangitis, and cyst infection may occur but synthetic function generally remains unaffected. Cysts in other organs may occur but tend to be clinically insignificant. The prevalence of cerebral aneurysms is 8-12%.

Diagnostic criteria are based on family history and the number of cysts as a function of age.

Genetic testing may be indicated in limited circumstances.

What treatments are recommended to slow the progression?

Aggressive BP control with ACEIs and ARBs may help but tolvaptan is a recently emerging treatment which is supported by the best evidence.

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