Page 259 - Medicine and Surgery

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Chapter 6: Disorders of the kidney 255

disease and interstitial fibrosis leading to gradual deteri- Management
oration of renal function. Supportive. Control of infection with antibiotics and
treat hypertension.
Development of end stage renal failure means that
Clinical features
Around two thirds of patients have a positive family his- dialysis or transplantation are needed.
Some patients require cyst decompression for in-
tory and the disease may be detected due to radiologi-
cal screening of family members. Patients may present tractable pain, or even nephrectomy if very enlarged
with loin pain, lumbar pain, haematuria, an abdominal kidneys cause symptoms such as tiredness and loss of
mass, hypertension or with chronic renal impairment. appetite.
Pyelonephritis, an infected cyst or bleeding into cysts Screen family members and offer genetic counselling
may occur, causing acute abdominal or lumbar pain and as appropriate.
haematuria in some cases.
On examination, bilateral, irregular abdominal mass- Prognosis
es may be palpable. The liver may also be enlarged. Approximately 25% of patients need dialysis by the age
of 50, 40% by age 60 and 50–75% by age 75. One third
Macroscopy die from complications of hypertension, particularly
Bilateralkidneyenlargementwithamassofcystsranging heart disease and stroke. Poor prognostic indicators in-
in diameter. clude younger age at diagnosis, Afro Caribbeans, males,
hypertension,PKD1geneandanepisodeofmacroscopic
haematuria.
Complications
Cysts develop in the liver in 40%, also in the lung and
pancreas. There is an association with berry aneurysms Simple renal cysts
(10–30%) of the cerebral arteries, which together with
hypertension, predisposes to subarachnoid haemor- Definition
rhage (SAH). The risk of SAH may be as high as 20% These are common, usually asymptomatic benign cysts
in those with a positive family history of SAH. of the kidney of unknown cause.
Unlike other causes of renal failure, in APKD erythro-
poietin levels are often preserved, preventing the devel- Incidence/prevalence
opment of anaemia. In some cases polycythaemia may Related to age and sex, with about 1–2% of 30–50 year
occur. olds, but as many as 15–30% in over 70 years, having one
There is also an association with heart valve disease, or more cysts.
diverticulosis and abdominal/inguinal hernias. Renal
stones may develop.
Age
There does not appear to be an increased risk of renal
Rare under the age of 30.
cell carcinoma, although the diagnosis of this is made
harder by the presence of multiple cysts.
Sex
M > F (2:1)
Investigations
Diagnosis is confirmed by renal ultrasound or IVU,
which shows large kidneys with long ‘spidery’ calyces. In Clinical features
children and young adults, the diagnosis may be missed Almost always asymptomatic and so tend to be found
as the cysts develop with age. In older people without incidentally on ultrasound, IVU or CT. They have no
APKD, simple cysts may occur, so over the age of 60, effect on renal function, except rarely when they may
four or more cysts in each kidney are needed to make induce hypertension. Occasionally they may become in-
the diagnosis. Genetic diagnosis is difficult because of fected or develop haemorrhage and rarely may become
multiple large genes with a diffuse spread of mutations. malignant.