BOF: 2.7
A 16-year-old male presents with a history of passing
blood in his urine. He gives a history of tonsillitis 3 weeks prior to the
onset of haematuria. On examination there is periorbital oedema and ankle
oedema and his blood pressure is elevated. Investigations reveal proteinuria
and uraemia.
In this patient, which of the following features seen on
light microscopy will confirm the diagnosis?
a)
Hyaline casts
b)
Fine granular casts
c)
Red cell casts
d)
White blood cells
e)
Bacteria
Answer:
c)
The clinical features suggest the patient has
glomerulonephritis.
Casts are formed by precipitation of Tamm-Horsfall
protein. Tamm-Horsfall protein is a glycoprotein, which is excreted by the
thick ascending loop of Henle and the first part of the distal tubules.
Hyaline casts and fine granular casts may be seen in normal urine particularly
after exercise. Red cell casts
indicate that the patient has glomerulonephritis.
White blood cells indicate an inflammatory reaction
within the urinary tract, most commonly infection. Bacteria in a clean-catch,
mid-stream urine suggest infection.
