Picture quiz: renal impairment
A 68 year old man with renal impairment was referred to a urology department. He had traces of blood and protein in his urine. He was clinically well and the examination was unremarkable.
The radiographs in figs 1, 2, and 3 were taken.
Normal urine is composed of a complex solution of ions, proteins, and inhibitory substances. Should the delicate balance between them change, crystals form which precipitate into stones. Predisposing factors for stone formation include dehydration, chronic urinary infection, excess secretion of stone forming substances, foreign bodies, and diseased tissue.
Most stones (60%-70%) are composed of calcium oxalate. Stones of magnesium ammonium phosphate make up the about 15% to 20% and the rest are composed of calcium phosphate (5%), uric acid (5%) and finally cystine (1%). Overall about 90% of stones are radio-opaque.
Initial investigations should be tailored towards confirming the suspected diagnosis and screening for renal function and