Investigations

• red blood cell shape ^b
• lymphocytes ^b
• eosinophils ^c
• casts ^b

Why?

Absence of dysmorphic red blood cells or the 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 glomerular abnormality on microscopy	4.9 (2.2 to 11)	13%	0.23 (0.13 to 0.42)	0.7%

Absence of lymphocytes, eosinophils or haem-granular casts on microscopy make interstitial 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: 2%)	interstitial disease (renal biopsy)	lymphocytes ≥10 per 10 high power fields on microscopy	3.0 (1.8 to 4.9)	6%	0.28 (0.13 to 0.63)	0.6%
		haem -granular casts on microscopy	1.7 (1.2 to 2.2)	3%	0.27 (0.089 to 0.79)	0.5%
		granular casts ≥5 per 10 high power fields on microscopy	2.1 (1.2 to 3.6)	4%	0.58 (0.35 to 0.96)	1.2%
under investigation for renal disease c (pre-test probability: 4.4%)	interstitial disease (renal biopsy or clinical features)	>1% eosinophils using Hansel's stain on microscopy	9.1 (4.2 to 20)	29%	0.40 (0.16 to 0.99)	2%