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

2. Case 1 • 22y female 3 day hx of dysuria, frequency and urgency. Afebrile. • Urine dip: +leuks, +nitrite, +RBC’s • Urinalysis:

3. Case 1 • 22y female 3 day hx of dysuria, frequency and urgency. Afebrile. • Urine dip: +leuks, +nitrite, +RBC’s • Urinalysis:

4. 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

5. 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

6. 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%

7. 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

8. 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

9. Case 2 • 18y f, 3d hx of dysuria, frequency and urgency • Dipstick +ve leuks, -ve for nitrite • Micro:

10. 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

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

12. Urine Culture • Provides definitive diagnosis • >105 CFU/mL considered positive • correlated with 95% likelyhood of infection • >104 CFU/mL correlated with only 50% likelyhood

13. 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

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

16. Case 3 • While working this pt up for presumed urosepsis a urine was sent off… • Micro

17. 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…

19. 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

21. 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

22. RBC cast

23. Granular cast Waxy cast

24. 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

25. 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

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

27. 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

28. Thanks!