ANSWER 22
Peripheral oedema may occur due to local obstruction of lymphatic or venous outflow, or
because of cardiac, renal, pulmonary or liver disease. Unilateral oedema is most likely to
be due to a local problem, whereas bilateral leg oedema is usually due to one of the med-
ical conditions listed above. Pitting oedema needs to be distinguished from lymphoedema
which is characteristically non-pitting. This is tested by firm pressure with the thumb for
approximately 10 s. If the oedema is pitting, an indentation will be present after pressure
is removed. This man has a subacute onset of massive pitting oedema. The major differ-
ential diagnoses are cardiac failure, renal failure, nephrotic syndrome, right heart failure
(cor pulmonale) secondary to chronic obstructive airways disease or decompensated chronic
liver disease. The frothy urine is a clue to the diagnosis of nephrotic syndromeand is com-
monly noted by patients with heavy proteinuria.
On examination there were no clinical signs to suggest chronic liver disease. The jugular
venous pressure would be expected to be more raised, and there should have been signs
of tricuspid regurgitation (prominent āvā wave, pansystolic murmur loudest on inspiration)
and cardiomegaly if the patient had cor pulmonale or biventricular cardiac failure. The
patient has signs of bilateral pleural effusions which may occur in nephrotic syndrome, if
there is sufficient fluid retention. The bruising and peri-orbital purpura is classically seen
in patients with nephrotic syndrome secondary to amyloidosis.
The investigations are consistent with the diagnosis of nephrotic syndrome. Nephrotic
syndrome is defined by the triad of hypoalbuminaemia (!30 g/L), proteinuria (#3 g/24 h),
and hypercholesterolaemia. The normochromic, normocytic anaemia is typical of chronic
disease and is a clue to the underlying diagnosis of amyloidosis. Patients with amyloido-
sis may have raised serum transaminase levels due to liver infiltration by amyloid.
The patient should have a renal biopsy to delineate the cause of the nephrotic syndrome. The
principal causes of nephrotic syndrome are listed below. Adults presenting with nephrotic syn-
drome should have a renal biopsy. The exception is the patient with long-standing diabetes
mellitus, with concomitant retinopathy and neuropathy, who almost certainly has diabetic
nephropathy.
- Diabetes mellitus
- Minimal change disease
- Focal and segmental glomerulosclerosis
- Membranous nephropathy
- Systemic lupus erythematosus
- HIV infection
- Amyloidosis/myeloma
! Causes of nephrotic syndrome
In this case renal biopsy confirmed the diagnosis of amyloidosis, and staining was posi-
tive for lambda light chains. Immunofixation confirmed the presence of a IgG(parapro-
tein in the blood. A bone marrow aspirate showed the presence of an excessive number of
plasma cells, consistent with an underlying plasma cell dyscrasia. Patients with amyloi-
dosis should have an echocardiogram to screen for cardiac infiltration, and if the facilities
are available a serum amyloid P scan should be arranged which assesses the distribution
and total body burden of amyloid. An amyloid P scan is shown in Fig. 22.1.