APPROACH TO A PATIENT WITH SUSPECTED KIDNEY DISEASE

1. APPROACH TO A PATIENT WITH SUSPECTED KIDNEY DISEASE ELIZABETH ROMANO-SEBASTIAN MD FPCP FPSN

2. A 28 yo female came to your clinic for bi pedal edema of 2 weeks duration. PE showed puffy eyelids, pale conjunctiva, + friction rub, decrease breath sounds and Gr 2 pedal edema. She denies any intake of any meds.

3. Creatinine • 2.4 mg/dl

4. ELECTROLYTES • Na – 138 • K – 5.5 • iCal – 4.8 • Phos – 3

5. URINALYSIS

6. Color Normal: pale to dark depending on the concentration of the urine. Pathologic conditions: gross hematuria hemoglobinuria myoglobinuria (pink, red, brown or black) ; jaundice (dark yellow to brown); chyluria (white,milky) massive uric acid crystalluria (pink) Drugs: rifampin (yellow-orange to red; phenytoin (red), nitrofurantoin (brown); metronidazole, imipinem, methyldopa (darkening on standing)

7. Odor • Pungent • UTI due to production of ammonia) • Sweet • ketones • Musty • pku

8. Turbidity • Usually transparent but can be due to inc concentration of any particle

9. FOAM • Indicates the amount of protein in the urine

10. Chemical Analysis Dipstick • pH • Hemoglobin • Glucose • Albumin • Leukocyte esterase • Nitrates • Bilirubin • Specific gravity

11. pH • presence of H+ ions due to the secretion of acid in the collecting duct • low ph: • metabolic acidosis, high protein meals, (generate more acid and ammonia) and with volume depletion- aldosterone is stimulated resulting in acidic urine) • high ph: • RTA, vegetable diets, infection with urease + like proteus) • Range: 5-8.5

12. Hemoglobin • Pseudoperoxidase activity of the heme moiety of Hgb, which catalyzes peroxide and chromagen ---colored product • False positive: • hemoglobinuria from intravascular hemolysis • myoglobinuria from rhabdomyolysis • high concentration of bacteria with enterobacter staphylococci, strep • False negative: • ascorbic acid

13. RBC- Hematuria – blood in the urine • Differentiated by centrifugation

14. Glycosuria • Used for testing • Multistix – glucose oxodase reaction • Clinitest – modified Benedict’s test for reducing substances • Types of glycosuria • Overflow glycosuria – above 180mg/dl • Renal glycosuria – associated with Fanconi Syndrome

15. Protein • Physiologic • Daily production – 40-150 mg/day • 40% albumin, 40% tissue, 15% Ig and fragments, 5% other plasma proteins • 150 mg/24 hrs adults, 140 mg/m2 in children • Method is sensitive to albumin • First morning Random protein crea ratio (same time for follow-up) • Types of Proteinuria • Overflow – contains Bence-Jones proteins, myoglobin, Hgb • Glomerular permeability • Selective - albumin • Non-selective • Tubular – decrease reabsorption of filtered protein; caused by antibiotics, heavy metals • Hemodynamic – caused by CHF, heat, seizures, exercise

17. Microscopic Examination Sediment Overview • Technique for preparation and examination • Morning specimen is the most concentrated • Centrifugation done in a conical tube for 3 to 5 minutes at 3000-5000 rpm • Pipetting • Decant supernatant liquid • Pipette while inverted • Aspirate button • May resuspend if too thick • Cover slip: avoid bubbles, examine periphery for formed elements

18. Examination • Scan entire entire field at low power • Magnify selected areas • Stop down diaphragm or move light source for contrast • Stain if necessary

19. Microscopic Formed elementsCellular elements WBC- easiest to find due to granular cytoplasm and lobulated nucleus • Marker for upper or lower tract infections • In women may be found as contaminant • May also be GN, Interstitial nephritis

20. RBC • Changing the focus, causes red cells to appear as black tires, appear concave • Normal • Dysmorphic RBC’s • Crenated RBC- occurs in hypertonic urine • Acanthocytes- doughnut-like with blebs (mickey mouse ears) • Discocyte→echinocytes→stomatocyte- transition inducible in changes in pH, osmolality and protein concentrations

21. Casts • Can only come from the tubules • Primarily Tamm- Horsfallmucoprotein • Secreted in TAL as monomers • Polymerized into casts in distal tubules and collecting ducts • Incorpotate material that is within the tubules • Favored by low flow rates, low pH, high luminal Na • Larger casts from larger tubules especially with decreased flows

22. Hyaline cast Fine granular cast

23. Broad coarsely granular cast Fatty cast Waxy cast

24. Acute Tubular Necrosis

25. RBC Cast- indicative of Glomerular injury

26. White Blood cell cast Acute interstitial nephritis, acute pyelonephritis, proliferative glomerulonephritis

28. pH 6 • Sg 1.02 • Protein ++++ • RBC 8/hpf • WBC 9/hpf • Epithelial cells many • RBC casts, fine granular casts

29. USG • Size • Cortical thickness • Echogenicity • Calyxes • Ureter • Normal sized kidneys with hypoechoic parenchyma

30. 54 yo male known hypertensive, known diabetic admitted for decreasing urine output

31. A 32 yo male known to have a solitary functioning R kidney came in for R flank pain radiating to the R testicle with no urine output for the past 8 hours

32. TAKE HOME MESSAGES • History and PE will determine the type of exams to be requested • In approaching a patient with elevated creatinine, the first step is to differentiate acute from chronic kidney disease • Trend of creatinine more important than a single determination • Proper collection of urine must be emphasized to a patient • Be systematic in interpreting laboratory results.