Investigations

• dysmorphic red blood cells ^b
• pigmented granular casts ^b

Note

• 'Pigmented granular' casts are also called 'haem-granular' or 'muddy brown' casts.

Why?

Absence of dysmorphic red blood cells or presence of haem-granular casts makes glomerular disease less likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
undergoing renal biopsy b (pre-test probability: 3%)	glomerular disease (renal biopsy)	dysmorphic red blood cells on microscopy	4.7 (2.3  to 9.6)	13%	0.080 (0.026 to 0.24)	0.2%
		haem-granular casts on microscopy	0.66 (0.48 to 0.92)	2%	2.3 (1.1 to 5.1)	6.6%
		any features of glomerular disease on microscopy	4.9 (2.2 to 11)	13%	0.23 (0.13 to 0.42)	0.7%