Page 248 - Medicine and Surgery

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244 Chapter 6: Genitourinary system

Goodpasture’s disease (anti-Glomerular Basement Investigations

Membrane (GBM) disease). Urinedipstickispositiveforbloodandmaybepositive
Systemic diseases such as systemic lupus erythe- for protein. Urine microscopy may demonstrate the

matosus (SLE), Henoch–Sch¨ onlein purpura (HSP), dysmorphic red blood cells and red cell casts, which
vasculitis (Wegener’s granulomatosis, polyarteritis), indicate a nephritic urine.
malignanthypertensionandhaemolytic-uraemicsyn- Patientsshouldbeinvestigatedasforacuterenalfailure
drome (HUS). (see page 234).
Renal biopsy is required in most cases to help iden-

Pathophysiology tify the underlying cause, deomonstrate the pattern of
Proliferation of endothelial cells and mesangial cells, or disease, indicate prognosis and guide management.
vasculitis, leads to occlusion of the capillary lumen, re- FBC and peripheral blood film particularly to look for
duced blood flow, oliguria and acute renal failure. Dam- thrombocytopenia, and evidence of haemolysis.
aged glomeruli leak red blood cells causing microscopic More specific tests which are useful in nephritic
(occasionally macroscopic) haematuria. The low GFR syndrome include:
also leads to activation of the renin–angiotensin sys- 1 ANA and anti-dsDNA (anti-double stranded DNA
tem, exacerbating hypertension. Proteinuria may also be antibody is specific for SLE)
present. 2 ANCA - Anti-neutrophil cytoplasmic Antibody
Focal nephritis: When less than 50% of the glomeruli
(found in vasculitides such as Wegener’s)
are affected this usually manifests as haematuria 3 Anti-GBM antibody
with or without minor proteinuria. The majority of 4 Complement C 3 and C 4 – these are low in certain
glomeruli are unaffected so renal failure is minimal or conditions.
absent. 5 ASO and anti-DNAase – these are evidence of a pre-
Diffuse nephritis: If more than 50% of the glomeruli
ceding streptococcal infection
are affected then oliguria and acute renal failure re- 6 Serum cryoglobulins
sults. If diffuse nephritis is severe (with crescents
in most of the glomeruli) then rapidly progressive
Management
glomerulonephritis results.
This is as for acute renal failure. Urgent treatment of
the underlying cause is often needed to prevent perma-
Clinical features nent loss of renal function and early referral to a renal
The full nephritic syndrome includes haematuria, pro- physician is necessary.
teinuria, hypertension and oedema (from salt and water
retention), oliguria and uraemia, but the features are
variably present. Often, the patient is unwell and there Acute diffuse proliferative
may be features of the underlying illness, for exam- glomerulonephritis
ple haemoptysis with Goodpasture’s syndrome, rash,
Definition
joint pains, a preceding infection, e.g. diarrhoea or a
A diffuse global glomerular disease, which is immune
sore throat. Headache and loin pains are common non-
complex mediated and usually precipitated by a preced-
specific features. Salt and water retention can lead to
ing infection.
hypertensive encephalopathy and pulmonary oedema.
Incidence
Macroscopy/microscopy
The commonest glomerulonephritis worldwide, falling
The kidneys are oedematous, swollen, with scattered pe-
in the United Kingdom.
techiae sometimes seen. The microscopic appearances
are described in greater detail in section on Glomeru-
lar Disease (see page 240) and under each individual Age
condition. Anyage, peak in schoolchildren.