Evaluation of Kidney Function

• Albuminuria


  Leaking of small amounts of albumin
• Albuminuria


  • First sign of renal insufficiency
  • Albumin-to-creatinine ratio (ACR) is the first method of preference to detect elevated protein
  • The recommended method to evaluate albuminuria is to measure urinary ACR in a spot urine sample
  • ACR is calculated by dividing albumin concentration in milligrams by creatinine concentration in grams
• When dealing with kidney patients, a lot of parameters are assessed; height and weight are not enough
• Albuminuria


  Albumin secreted in urine
• Detecting albuminuria


  1. Doctor may request urinalysis

  2. When you have the urine sample, albumin is present in the urine
• Nephrotic syndrome


  Too much albumin in the kidney
• The magic number is 30, if it reaches 30, you are a candidate for CKD
• This detects the elevated protein in the urine
• They calculate the albumin concentration by the creatinine concentration
• In CKD, you need to have consistent (2 out of 3) urine samples that there is positive albumin within 3 months
• Glomerular Filtration Rate (GFR)


  • Measures kidney function
  • Reflected in clearance tests that measure the rate at which substances are cleared from the plasma by the glomeruli
  • Used to evaluate kidney health, estimate the severity of disease and monitor disease progression
  • Measures how well your kidneys filters blood and determines the stage of CKD
• ACR


  How much protein in urine
• GFR


  How good is your kidney in filtering
• ACR has 3 stages, GFR has 5
• CKD is defined as either GFR is less than 60 for 3 months or longer
• Stages of CKD will be evaluated with ACR or GFR
• Cockroft-Gault equation


  If male, 0.85 factor is removes
• Modification of Diet in Renal Disease Study

  • One of the risk factor is race
  • Not that used since it is race specific. Different parts of Asia made their own. It is restrictive
  • Most of the time the cockroft-gault is used
• Serum Creatinine


  • As kidney function decreases, levels start to increase
  • Cannot be used to measure GFR
  • Kidneys malfunctions, creatinine is increasing
  • They have an inverse relationship
• Blood Urea Nitrogen (BUN)


  • From protein breakdown
  • Decreased kidney function: increase BUN level
  • Normal Range: 7-20 mg/dL (2.5-7.1 mmol/L)
  • BUN is dietary related
  • If you eat too much meat, you'll have excess protein leading to excess waste (nitrogen)
  • As the kidney function decreases BUN rises
  • They have an inverse relationship similar to serum creatinine
• As kidney disease progresses, the level of creatinine and BUN in the blood rises
• When we check laboratory results, they always come in "pair"
• If they are both high, it is usually a sign of kidney disease
• Both are waste
• If only one is high, this is related to muscle function
• If you deal with pediatrics, creatinine is observed due to the possible occurrence of wasting
• Important that BOTH values are high or low when it comes to renal cases
• Ultrasound


  • Uses sound waves to get a picture of the kidney
  • Used to look for abnormalities in size or position of the kidneys or for obstructions such as stones or tumors
  • Imaging is also used to see if there are possible obstructions that might compromise kidney functions
• CT Scan


  • Imaging technique uses X-rays to picture the kidneys
  • May also be used to look for structural abnormalities and the presence of obstructions
  • May require the use of intravenous dye which can be of concern ofr those with kidney disease
• IV contrast dye


  • Controversial
  • You might encounter patients with allergies, they might be allergic to the dye which can have detrimental effects
  • That is why we have options such as ultrasound
  • May be a concern for some kidney disease
• Contrast Induced Nephropathy (CIN)


  • Mainly caused by the CT scan with the use of the dye
  • Risk Factors: Pre-existing CKD, Heart/blood vessel problem, Old age
• Nephrogenic Systemic Fibrosis (NSF)


  Mainly caused by the MRI with contrast dye
• Ultrasound and CT scan uses small doses of radiation whereas MRI uses powerful magnets
• Urinalysis


  • Can help detect a variety of kidney and urinary tract disorders, including chronic kidney disease, diabetes, bladder infections and kidney stones
  • Common in biochemical tests
  • Observed here is the protein, if how much is being excreted through urination
• Urine Protein


  • To detect presence of excess amount of protein in the urine (+)
  • 2+ is an alarming reading, ⅔ trials possible sign of kidney disease