1 / 19

Renal Physiology and Function Part II Renal Function Tests

Renal Physiology and Function Part II Renal Function Tests. Ricki Otten MT(ASCP)SC uotten@unmc.edu. Renal Function Tests. Tubular Reabsorption Glomerular Filtration Renal Blood Flow Tubular Secretion. Tubular Reabsorption Tests. Can the kidneys concentrate urine

damisi
Download Presentation

Renal Physiology and Function Part II Renal Function Tests

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Renal Physiology and Function Part IIRenal Function Tests Ricki Otten MT(ASCP)SC uotten@unmc.edu

  2. Renal Function Tests • Tubular Reabsorption • Glomerular Filtration • Renal Blood Flow • Tubular Secretion

  3. Tubular Reabsorption Tests • Can the kidneys concentrate urine • “Concentration Tests”: control of fluid intake important in interpretation of test • Fluid deprivation • Free water clearance

  4. Tubular Reabsorption Tests • Laboratory: • Specific gravity (number and density) • Refractometer • Reagent strip • Osmolality (number of particles in solution) • Better test • More accurate

  5. Glomerular Filtration Tests • Assess filtering ability of glomerulus • “Clearance tests” • Measures the RATE at which kidneys can clear a ‘filterable’ substance from the blood • This substance must not be reabsorbed or secreted by the tubules • GFR = glomerular filtration rate

  6. Glomerular Filtration Tests • Specimen requirements • Timed urine specimen: 24 hour collection • Plasma sample • Clearance calculation: UV = ml/min P

  7. Glomerular Filtration Tests • Endogenous • Creatinine (most common) • Exogenous • Inulin (considered the ‘standard’)

  8. Glomerular Filtration Tests • Creatinine clearance test • Endogenous substance (found in the body) • Produced at a steady rate • Dependent on muscle mass (male, female, child, adult) • Thus ‘normalized’ to body surface area using a nomogram • Children • Obese

  9. Glomerular Filtration Tests • Calculate creatinine clearance: UV P Urine creatinine (U) 185 mg/dl Plasma creatinine (P) 0.9 mg/dl Urine volume (V) 1250 ml/24 hr Height 6’0” Weight 260 lb

  10. Calculate Creatinine Clearance CrCl = UV P

  11. Calculate Creatinine Clearance UV = 185 mg/dl x 1250 ml x 1 hour = 178.4 = P 0.9 mg/dl 24 hours 60 min CrCl = 178 ml/min

  12. Calculate Creatinine Clearance UV = 185 mg/dl x 1250 ml x 1 hour = 178.4 = P 0.9 mg/dl 24 hours 60 min CrCl = 178 ml/min Is this normal for a 20 year old male?

  13. Calculate Creatinine Clearance UV = 185 mg/dl x 1250 ml x 1 hour = 178.4 = P 0.9 mg/dl 24 hours 60 min CrCl = 178 ml/min Is this normal for a 20 year old male? No, it is increased Correct value for body surface area

  14. Corrected Creatinine Clearance CrCl = 178 ml/min Corrected CrCl = CrCl x 1.73m2 = 178 ml/min x 1.73 BSA 2.39 = 128.8 = 129 ml/min

  15. Corrected Creatinine Clearance CrCl = 178 ml/min Corrected CrCl = 129 ml/min Is this normal for a 20 year old male?

  16. Corrected Creatinine Clearance CrCl = 178 ml/min Corrected CrCl = 129 ml/min Is this normal for a 20 year old male? Yes

  17. Renal Reserve • Large margin of reserve in renal function • Greater than 50% of kidney function must be lost before • Clinical symptoms apparent • Biochemical abnormalities evident • Thus, not useful for screening for early renal disease

  18. Renal Blood Flow • Tubular Secretion No objectives

More Related