Check the pee Lab rounds Aug 7 th, 2008 Kristian Hecht

Case 1 22y female 3 day hx of dysuria, frequency and urgency. Afebrile. Urine dip: +leuks, +nitrite, +RBC’s Urinalysis: RBC200-5/hpf WBC300-5/hpf EpithelialFew0/hpf BacteriaMany0/hpf CastsNone0/hpf

Case 1 22y female 3 day hx of dysuria, frequency and urgency. Afebrile. Urine dip: +leuks, +nitrite, +RBC’s Urinalysis: RBC200-5/hpf WBC300-5/hpf EpithelialFew0/hpf BacteriaMany0/hpf CastsNone0/hpf

Dipsticks in UTI Multisticks measure Sp. gravity, pH, glucose, nitrites, protein, leuks, rbc’s, bili, ketones Leuks and nitrites are the most useful in suspected UTI

Dipsticks WBC’s measured indirectly measuring leukocyte esterase activity LE contained in neutrophils and macrophages Sp 80-90% Sn 75-96% False –ve’s: high glc, high prot, tetracycline, keflex

Dipsticks Nitrites produced by most Gm –ve uropathogens Not produced by Pseudomonas or Enterococcus Diet must contain nitrates to be +ve Sn <50% Sp >90%

Dipsticks In children <12y, when compared to microscopy, urine dips were equally as accurate Pediatrics 104:54, 1999 Less accurate in children <2y In adults with a typical UTI hx, some advocate for empiric tx with no further investigation based on a +ve dip

Microscopy Urine spun at 2000rpm for 5 min Sediment is resuspended in remaining urine and examined + gram staining WBC’s –>5/hpf in females, >2/hpf in males Bacteria –>15/hpf

Case 2 18y f, 3d hx of dysuria, frequency and urgency Dipstick +ve leuks, -ve for nitrite Micro: RBC10-5/hpf WBC300-5/hpf Epithelial00/hpf Bacteria00/hpf CastsNone0/hpf

Microscopy WBC’s –False negatives: dilute urine, leukopenia, partial treatment Bacteria –Negative if: C. trachomatis, N. gonorrhea, HSV, S. saprophyticus –False –ve if: dilute urine, low bacterial load

Case 2 con’t Further hx indicates recent unprotected intercourse with a new partner 10d ago Swabs taken Teachable moment seized

Urine Culture Provides definitive diagnosis >10 5 CFU/mL considered positive correlated with 95% likelyhood of infection >10 4 CFU/mL correlated with only 50% likelyhood

Urine Culture False +ve cultures are common due to contamination from uropathogens on the perineum and foreskin Many studies show that urine culture is only useful when the diagnosis is uncertain or when there are host factors that make pathogen identification important

Groups in Which Urine Culture is Indicated 1. Children 2. Adult men 3. Immunocompromised patients 4. "Treatment failure" (recently completed course of antibiotics with persistent urinary symptoms) 5. Patients with symptoms in excess of 4 to 6 days 6. Elderly patients at risk for bacteremia 7. Toxic-appearing patients with signs and symptoms suggestive of pyelonephritis or bacteremia 8. Pregnant women 9. Patients with known chronic or recurrent renal infection 10. Patients with known anatomic urologic abnormalities 11. Patients in whom urinary tract obstruction is suspected (e.g., stones, benign prostatic hypertrophy) 12. Patients with serious medical diseases, including diabetes mellitus, sickle cell anemia, cancer, or other debilitating diseases 13. Patients with alcoholism, drug dependence 14. Recently hospitalized patients 15. Patients taking antibiotics 16. Patients recently instrumented (e.g., cystoscopy, catheterization)

Case 3 75y male unresponsive, tachycardic, hypotensive, afebrile Had complained of flank pain 24h ago Hx of BPH and mild UTI’s in past

Case 3 While working this pt up for presumed urosepsis a urine was sent off… Micro pH6.0 RBC100-5/hpf WBC20-5/hpf EpithelialMod - Necrotic renal tubular cells 0/hpf BacteriaFew0/hpf CastsMany – epithelial casts 0/hpf CrystalsMany - Oxalate mono/dihydrate 0/hpf

Case 3 A neighbor comes by the ICU the next day and mentions that the pt had seemed depressed lately. Pt also asked to borrow some antifreeze for his car 3 days ago…

Crystals Crystals may be normally found in urine based on diet, concentration and pH –Urate, oxalate Pathologic crystals –Cholesterol – indicates marked proteinuria –Cystine – familial cystinuria –Drugs (Acyclovir, Amoxil, Cipro, Indinavir) Can be implicated in cases of ATN

Casts Form when urinary ‘Tamm-Horsfall’ proteins precipitate with low pH or incr. concentration Cellular debris can become entrapped in this precipitate May help differentiate causes of acute renal failure and renal disease

RBC cast

Granular cast Waxy cast

Casts Acute tubular necrosis –necrotic renal tubular epithelial cells (RTEC) –RTEC casts Proliferative/Necrotic GN/vasculitis – erythrocytic casts Rhabdomyolysis – myogolbin casts Calcium oxalate crystals – ethylene glycol

Casts Nephrotic syndrome –Proteinuria, lipuria with RTEC and fatty casts Degree of hematuria can indicate underlying cause (mininmal change, membranous, focal segmental…) Nephritic syndrome –Mod/Severe dysmorphic hematuria RTEC casts and/or waxy casts

Other Casts Hyaline – prerenal azotemia, normal Granular – renal disease of any cause Leukocytic – Pyelonephritis/acute interstitial nephritis

Take home goodies Think about STI’s when the microscopy doesn’t fit with the story/dip Don’t culture everyone Crystals and casts can be useful in differentiating causes of ARF

Thanks!