Chronic renal failure laboratory tests: Difference between revisions
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[[Kidney]] plays an important role in regulation of serum concentration of [[sodium]], [[potassium]], [[calcium]], [[phosphate]], [[bicarbonate]] and [[chloride]] as well as levels of [[hemoglobin]], [[hematocrit]], [[blood pressure]] and extracellular volume. Hence, chronic injury to the [[kidney]] can lead to derangement in the normal values of above mentioned parameters. | [[Kidney]] plays an important role in regulation of serum concentration of [[sodium]], [[potassium]], [[calcium]], [[phosphate]], [[bicarbonate]] and [[chloride]] as well as levels of [[hemoglobin]], [[hematocrit]], [[blood pressure]] and extracellular volume. Hence, chronic injury to the [[kidney]] can lead to derangement in the normal values of above mentioned parameters. | ||
==Urinalysis== | ==[[Urinalysis]]== | ||
*[[Albuminuria]] | *[[Albuminuria]] | ||
*[[Urine]] [[sodium]] excretion ( | *[[Urine]] [[sodium]] excretion ([[Fractional excretion of sodium]]): | ||
*:* More useful for [[Acute renal failure]] to distinguish prerenal state from [[acute tubular necrosis]] (ATN) | *:* More useful for [[Acute renal failure]] to distinguish prerenal state from [[acute tubular necrosis]] (ATN) | ||
*:* May '''not''' be low in volume depleted [[chronic renal failure]] patients due to tubular dysfunction | *:* May '''not''' be low in volume depleted [[chronic renal failure]] patients due to tubular dysfunction | ||
*[[Hematuria]] | *[[Hematuria]] | ||
*[[Pyuria]] | *[[Pyuria]] | ||
*Red cell or white cell casts and crystals | *Red cell or white cell [[casts]] and crystals | ||
*[[Urine]] [[creatinine]] levels | *[[Urine]] [[creatinine]] levels | ||
*[[Albumin]] : [[Creatinine]] ratio is used to determine [[albumin]] excretion per day. | *[[Albumin]] : [[Creatinine]] ratio is used to determine [[albumin]] excretion per day. | ||
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*:* Determined by [[glomerular filtration rate]] ([[GFR]]) '''and''' by generation, tubular secretion and extrarenal clearance of [[creatinine]] | *:* Determined by [[glomerular filtration rate]] ([[GFR]]) '''and''' by generation, tubular secretion and extrarenal clearance of [[creatinine]] | ||
*:* May be inaccurate estimate of function, particularly in patients with mild renal insufficiency | *:* May be inaccurate estimate of function, particularly in patients with mild renal insufficiency | ||
*:* Drugs may inhibit tubular secretion of [[creatinine]] and falsely elevated serum [[creatinine]] ([[cimetidine]], [[trimethoprim]] | *:* Drugs may inhibit tubular secretion of [[creatinine]] and falsely elevated serum [[creatinine]] ([[cimetidine]], [[trimethoprim]]) | ||
* [[Creatinine clearance]] | * [[Creatinine clearance]] | ||
*:* Estimate: [(140-age) x body wt (kg)] / [Plasma [[creatinine]] x 72] (multiply result x 0.85 for women) | *:* Estimate: [(140-age) x body wt (kg)] / [Plasma [[creatinine]] x 72] (multiply result x 0.85 for women) | ||
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* Prior [[creatinine]] measurements if available | * Prior [[creatinine]] measurements if available | ||
* [[Acute Renal Failure]] (ARF) associated with: | * [[Acute Renal Failure]] (ARF) associated with: | ||
*:* Precipitating factor ([[nephrotoxin]], volume depletion, [[ | *:* Precipitating factor ([[nephrotoxin]], volume depletion, [[urinary tract obstruction]]) | ||
*:* More symptoms at given level of [[Creatinine]] | *:* More symptoms at given level of [[Creatinine]] | ||
*:* Lesser degree of [[anemia]], [[hypocalcemia]], [[hyperphosphatemia]] | *:* Lesser degree of [[anemia]], [[hypocalcemia]], [[hyperphosphatemia]] | ||
Revision as of 16:29, 26 July 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2]
Overview
Kidney plays an important role in regulation of serum concentration of sodium, potassium, calcium, phosphate, bicarbonate and chloride as well as levels of hemoglobin, hematocrit, blood pressure and extracellular volume. Hence, chronic injury to the kidney can lead to derangement in the normal values of above mentioned parameters.
Urinalysis
- Albuminuria
- Urine sodium excretion (Fractional excretion of sodium):
- More useful for Acute renal failure to distinguish prerenal state from acute tubular necrosis (ATN)
- May not be low in volume depleted chronic renal failure patients due to tubular dysfunction
- Hematuria
- Pyuria
- Red cell or white cell casts and crystals
- Urine creatinine levels
- Albumin : Creatinine ratio is used to determine albumin excretion per day.
Fluid and Electrolyte disturbances
- Hypervolemia
- Hyponatremia
- Hyperkalemia
- Hyperphosphatemia
- Hyperchloremia
- Metabolic acidosis
- Most often is mild, pH is rarely below 7.35
- Hypocalcemia
Endocrine and Metabolic disturbances
- Hyperuricemia
- Hypertriglyceridemia
- Decreased HDL levels
- Vitamin D deficiency
- Increased Parathyroid hormone levels
Hematologic abnormalities
Measurement of Renal Function
- Serum creatinine (Cr)
- Determined by glomerular filtration rate (GFR) and by generation, tubular secretion and extrarenal clearance of creatinine
- May be inaccurate estimate of function, particularly in patients with mild renal insufficiency
- Drugs may inhibit tubular secretion of creatinine and falsely elevated serum creatinine (cimetidine, trimethoprim)
- Creatinine clearance
- Estimate: [(140-age) x body wt (kg)] / [Plasma creatinine x 72] (multiply result x 0.85 for women)
- Calculated based on 24-hour urine collection
- Creatinine clearance (mL/min) = [Urine Creatinine (mg/dL) x Urine volume (mL/d)] / [Plasma Creatinine x 1440]
- If GFR < 50, Creatinine clearance overestimates GFR
- Calculate 24-hour blood urea nitrogen (BUN) clearance (underestimates GFR)
- Average of BUN and Creatinine clearances = GFR
Determination of Chronicity
- Prior creatinine measurements if available
- Acute Renal Failure (ARF) associated with:
- Precipitating factor (nephrotoxin, volume depletion, urinary tract obstruction)
- More symptoms at given level of Creatinine
- Lesser degree of anemia, hypocalcemia, hyperphosphatemia
- Chronic renal failure associated with:
- Greater likelihood of hematologic and biochemical abnormalities
- Bilateral small kidneys on ultrasound (though can be normal in chronic disease)