Renal exam-structure and fxn of kidney

  1. amount of plasma filtered
    25%-filtrate in glomerulus goes to urine, rest to efferent arterioles, forced in due to pressure difference, forced out of capillaries and into bowman's capsule
  2. primary determinant of arterial tone
    PGs, overrides effect of AT II normally, causes vasodilation, more blood flow, more filtrate produced, increases GFR, ATII vasoconstriction decreases amt of blood entering and decreases GFR
  3. drugs that affect arteriole tone
    NSAIDs-inhibit PG synthesis, increase arterial tone, vasoconstriction due to increased activity of AT II, decrease in GFR
  4. determinant of arterial tone and effect on GFR for efferent
    ATII is primary, constriction, increase pressure and increase GFR
  5. drugs affecting efferent arteriole
    ACE inh and ARBs, vasodilation, decrease GFR
  6. proximal convuluted tubule
    reabsorption, major site of ammonia production, 75%
  7. loop of henle
    reabsoption-additional 25%, concentration/diluting urine
  8. distal convuluted tubule
    final concentration of urine, 5-10% reabsorbed
  9. cortical collecting tubules
    reasorb NaCl and secrete K in response to aldo, reabsorb water due to ADH
  10. endocrine fxns of kidneys
    erythropoietin, prod and secretion of renin by juxtaglomerular apparatus in response to decrease afferent arteriole pressure, decrease renal flow or increase in renal sympathetic activity
  11. metabolic fxns of kidney
    activation of Vit D3, gluconeogenesis, metabolism of endogenous compounds and drugs (e.g. steroilds, insulin) P450 enzymes
  12. excretion=
    filtration + secretion-reabsoprtion
  13. filtrated substances
    H20, electrolytes, glu, small aa, creatinine
  14. size allowed to be filtered
    less than 50 angstroms, alb 35
  15. molecular wt filtered
    less than 20,000 daltons, alb 65,000
  16. charge filtered
    only +, alb is -
  17. protein binding affect on filtered substances
    only unbound, bound are secreted renally, abx, pcn, ceph
  18. role of tubular secretion
    maintain acid base and potassium balance, H, K, NH4, organic acids and bases, creatinine, protein-bound drugs
  19. role of tubular reabsorption
    reabsorb important compounds from filtrate back into blood
  20. normal urine volume
    500-1600 ml/day
  21. urine pH
  22. specific gravity of urine
    1.003-1.030, <1.010 relatively hydrated, >1.010 dehydrated
  23. osmolarity of urine
    50-1200mOsm/kg, assesses ability of tubules to concentrate urine (fxn of ADH)
  24. substances not normally found in urine
    glucose, protein, ketones, nitrites, lukocyte esterase, RBC, WBC and casts
  25. normal protein amts found in urine
    <10mg/dl, alb <30mg/gm Cr
  26. normal amt of RBC, WBC and casts found in urine
    0-1 RBC, <5 WBC and occassional cast
  27. factors affecting creatinine
    aging, muscle mass, diseases, diet, drugs (trim, cimet, fenof increase SCr by competing with tubular secretion, chronic steroid use decreases SCr due to decrease muscle mass), tubular secreation
  28. 24 hours creatinine clearance (ml/min)
    CrCl=Ucr X V/Pcr, needs to be refrig, large possibility of error, Ucr (conc of creatinine in urine at end of collection(mg/dl), Vm urine flow rate(ml/min), Pcr concentration of creatinine in plasma at midpoint of collection
  29. unstable creatinine
    rises by 0.5 mg/dl or more when baseline <3 mg/dl, or creatinine rises by 1 mg/dl or more when baseline creatinine is 3 mg/dl or more
  30. when to use MDRD (modification of diet in renal disease)
    more accurate than cockcroft-gault in pts with chronic kidney disease, diabetes, or transplanted kidneys
  31. MDRD not validated in:
    under 18 or over 70, pregnant, racial groups other than caucasians and african-americans
  32. when to use cockcroft-gault equation for estimating creatinine cl
    older pts, better to round to 0.8 instead of 1
  33. when to use 24 hours urine collection for creatinine cl
    prego, extreme ages and weights, pts with malnutrition, pts with skeletal muscle diseases, pts with para or quad, vegetarians and rapidly changing kidney fxn,
  34. compensating for amputations in cockcroft-gault
    calc LBW using ht prior to amp, calc effect of limb as a % of LBW, subtract % from LBW
  35. % loss single, below knee
  36. & loss, single at knee
  37. % loss, single above knee
  38. % loss, double below knee
  39. % loss at knee
  40. % loss above knee
Card Set
Renal exam-structure and fxn of kidney
exam 1