Nephrology for MRCPI Part 1

A 24-year-old man presents with visible haematuria occurring 24 to 48 hours after the onset of a sore throat, on three separate occasions over two years. Blood pressure 128/78 mmHg, creatinine normal, urine protein:creatinine ratio mildly raised. Complement C3 and C4 are normal. What is the most likely diagnosis?

1. Thin basement membrane disease Causes persistent microscopic haematuria with a benign course, not recurrent visible haematuria synchronised to pharyngitis.
2. IgA nephropathy correct Correct. Synpharyngitic haematuria, visible haematuria within one to two days of an upper respiratory infection, with normal complement is characteristic of IgA nephropathy, the commonest primary glomerulonephritis worldwide.
3. Post-streptococcal glomerulonephritis Wrong on timing and complement. It follows infection by one to three WEEKS, not one to two days, and complement C3 is low.
4. Alport syndrome Possible in a young man with haematuria, but it is associated with sensorineural deafness and a family history of renal failure, and the haematuria is persistent rather than episodic and infection-triggered.
5. Membranoproliferative glomerulonephritis Wrong. It typically presents with nephritic or nephrotic features and LOW complement.

The point: Timing separates the two commonest post-infectious glomerular presentations: IgA nephropathy is synpharyngitic with normal complement; post-streptococcal disease lags by weeks with low C3. Manage IgA nephropathy with blood pressure control and renin-angiotensin blockade, reserving immunosuppression for progressive disease.

Source: KDIGO clinical practice guideline for the management of glomerular diseases KDIGO · tier 2, specialty society or college