GI/GU/Liver #6 Flashcards
What is the normal glomerular filtration rate (GFR)?
90 - 125 mL/min
What does the GFR depend on?
- Permeability of capillary walls
- Vascular pressure
- Filtration pressure
What is the normal range for specific gravity?
1.003 to 1.050
Normal range for BUN:
6 - 20 mg/ dL
Blood Urea Nitrogen
Urea is an end product of protein metabolism (nitrogen).
Insufficient urea excretion from the blood elevates BUN levels. The BUN test detects renal problems IN CONJUNCTION with the creatinine test.
This test is more reliable than the BUN as a determinant of kidney function:
Creatinine.
Creatinine is a by-product of the normal breakdown of muscle tissue. Can be elevated after a workout and may also be higher in athletes due to their increased muscle mass.
Severe persistent renal impairment is virtually the ONLY reason that creatinine levels will rise!
What is the normal lab range for creatinine in our blood?
0.6 to 1.3 mg/dL
What test assesses the GFR to determine how efficiently the kidneys are clearing creatinine from the blood?
Creatinine Clearance.
24 hour urine collection. Method: when patient begins the test they must urinate and discard that sample because it was filtered before the test began. Once their bladder is empty, the test has officially started. They must collect every drop for the next 24 hrs in a container that contains preservatives, in the fridge.
Consideration: any patient that exhibits confusion will not be able to carry out this test successfully.
This test is the most accurate indicator of renal function:
Creatinine Clearance.
Because almost all of the creatinine in the blood is normally excreted by the kidneys. If creatinine is high = renal issue.
About how many mL triggers the urge to urinate?
200 - 250 mL
What are some gerentologic considerations with kidneys/urine output?
They may have physiologic changes:
- decreased kidney size and weight
- decreased renal blood flow (resulting in decreased GFR)
- Altered hormonal levels (resulting in decreased ability to concentrate urine, altered excretion of water, sodium, potassium and acid)
- Loss of elasticity and muscle support
- Prostate enlargement
- Decreased # of nephrons and in loop of Henle function.
Who are more predisposed to get a nephrolithiasis?
Calculi are more common in men, 20-55, whites, family history
Tend to recur
May form anywhere in the tract but USUALLY in the renal pelvis or calyces.
Where does the RAAZ system start?
In the glomerulus.
If urine output is less than 30mL/hr, what do we call this?
Oliguria.
What diagnostics are to be done to determine the health of a patients kidneys? Besides BUN and creatinine:
- CT with and without contrast (contrast can be nephrotoxic)
- IVP: IV contrast material - visualization of urinary tract NOT for pts with decreased renal function! (contrast)
- KUB (kidneys, ureters, bladder): simple x-ray, no contrast.
- MRI: not good for stone detection
- Ultrasound: speed, direction and blood flow
- VCUG: voiding study to visualize bladder filling and excretion of contrast as patient voids.
- Renal angiography: renal vasculature and parenchyma (contrast medium!)
Calculi form from precipitated substances that are normally dissolved in the urine, such as calcium phosphate.
They unite to form a stone. May occlude outflow from kidney.
The increasing frequency and force of peristaltic contractions cause pain.
Normal range for PaCO2:
35-45
Normal range for PaO2:
80 - 100 mm Hg
Normal range for HCO3:
22 - 26 mEq/L
bicarbonate is an intermediate form in the deprotonation of carbonic acid.
Bicarbonate serves a crucial biochemical role in the physiological pH buffering system.
Oxygen saturation (SaO2) normal range:
Over 95%
Refers to percent of hemoglobin saturated with O2.
What does the mnemonic “ROME” stand for?
RO : Respiratory - Opposite. When pH and CO2 are opposite then indicates Respiratory Alkalosis/Acidosis (determined by pH).
ME : Metabolic - Equal. When pH and HCO3 are both up/down (equal) then indicates metabolic alkalosis/acidosis.
What 2 values are considered with metabolic acidosis/alkalosis?
pH and HCO3
If both up = Alkalosis
If both down = Acidosis
What 2 factors are considered when determining Respiratory acidosis/Alkalosis?
pH and PCO2
PCO2 = Partial pressure of carbon dioxide in the blood
What are the 3 classifications of AKI or AKF?
Acute Kidney Injury or Acute Failure are classified by location:
1. Pre-renal, which is the most COMMON: inadequate perfusion, volume loss, impaired flow (HypoV shock, crushing injuries, hemorrhage, anaphylaxis, low BP, decreased CO, HTN, MI, renal artery stenosis). Anything that would affect blood flow to kidneys.
- Renal: aka intra-renal, glomerulus/tubules… structural damage to kidney tissues. #1 cause is ATN, Acute Tubular Necrosis - cell damage and waste products built up. Possibly from nephrotoxic drugs, contrast media, polycythemia, myoglobin, infection, cancer.
- Post-renal: obstruction. Kidney stone, prostate, BPH cancer, uretal destruction. Tubular pressure increases leading to decrease in the forces of filtration… causes backflow of urine leading to hydronephrosis (least common).
What are the three PHASES of AKI?
- Oliguric/Anuric phase.
Decreased volume output (less than 30mL/hr for 2 hours or 80-400 mL/day) - Diuretic Phase:
Kidney function improving (1-5L! output/day), at risk for FVD, hypokalemia, hyponatremia, GFR improving, may last 1-3 weeks. - Recovery Phase:
May last 2-12 months, needs to ambulate and drink a lot! Gradual return, older adults may not recover as well.
