- A low-molecular-weight protein produced by nucleated cells.
- It is freely filtered by the glomerulus, reabsorbed, and catabolized by the proximal tubule.
- Produced at a constant rate, levels remain stable if kidney function is normal.
- Plasma concentrations appear to be unaffected by gender, race, age, and muscle mass.
cystatin c
excretion test
- Measures renal plasma flow.
- REFERENCE METHOD FOR TUBULAR FUNCTION
Para-amino Hippurate Test (Diodrast Test)
concentration test
- Difference between measured and calculated osmolality.
- Sensitive indicator of alcohol or drug overdose.
- Osmolal Gap: >12 mOsm/kg
- DKA, Drug overdose, Renal failure
osmolal gap
measurement is important in the management of patients with diabetes mellitus, who are at serious risk of developing nephropathy over their lifetimes.
microalbumin
Creatinine clearance normally decreases with age, with a decrease of about (?) mL/min per (?) m2 for each decade of life
- 6.5
- 1.73
- Standard method to determine GFR.
- Values is derived by mathematically relating the serum concentration to the urine concentration excreted during a period of time, usually 24 hours.
- Specimen: (1) 24-hour Urine Specimen (kept refrigerated); (2) Serum Creatinine (collected at the midpoint of 24-hour urine collection)
creatinine clearance test
- Measurement of is used clinically to assess renal tubular function in renal transplant patients, with elevated levels indicating organ rejection.
- Remain stable in normal patients.
- Elevated levels in serum indicate increased cellular turnover in cases of inflammation, and renal failure.
B trace protein
- was one of the first clearance tests performed.
- it does not provide a full clearance assessment and is no longer widely used
urea clearance test
- Measurement to be at least as useful.
- (A rise is often detectible before there is a measurable decrease in GFR or increase in creatinine).
- Potentially more useful for detecting minor renal impairment.
- can be measured by IMMUNOASSAY METHODS
cystatin c
- The rate at which creatinine and urea are removed or cleared from the blood into the urine
- defined as that volume of plasma from which a measured amount of substance can be completely eliminated into the urine per unit of time expressed in milliliters pe rminute.
- Measurement is used to estimate the rate of glomerular filtration (ENDOGENOUS, EXOGENOUS TEST).
clearance test
concentration test
The density of a solution compared with that of a similar volume of distilled water influenced by both the number and size of the particles present
specific gravity
concentration test
- Total number solute particles present/kg of solvent (moles/kg solvent).
- Affected only by number of solutes present.
- Urine Osmolality = Urea
- Serum Osmolality = Na+ & Cl-
osmolality
Volume of plasma filtered by glomeruli per unit time
clearance
- Ideal substance for the measurement of clearance.
- It is not reabsorbed and is only slightly secreted by the proximal tubule.
- Serum levels are higher in males
- Analysis is simple and inexpensive using colorimetric assays.
- Helpful in monitoring renal function over time
creatinine clearance test
excretion test
- Measures excretion of dye proportional to renal tubular mass
- 6 mg of PSP is administered IV
Phenolsulfonthalein Dye Test
- Use to assess glomerular filtration or tubular secretion.
- Time consuming, expensive, and difficult to administer.
- REFERENCE METHOD TO ASSESS GFR.
inulin clearance test
