Week 4: Kidney injury, renal failure Flashcards
Role of Kidneys
- Production and excretion of urine.
- Excretion of urea (this is a by product of protein metabolism).
- The kidneys maintain the pH balance (acid and base) throughout the body.
- Regulation of the amount of water that is retained and excreted by the body.
- Assistance with fluid and electrolyte balance throughout the body.
- Production of Erythropoietin hormone (which has a role in the production of red blood cells).
- Compensatory functions (such as assistance with increased/decreased blood pressure).
Na+, K+, Cl-, Ca2+, Phosphorus, Magnesium Norms?
Electrolyte
Normal Range
Sodium (Na+) 135-145 mEq/L
Potassium (K+) 3.5-5 mEq/L
Chloride (Cl-) 100-110 mEq/L
Calcium (Ca2+) 8.5-10.0 (total) mg/dL
Phosphorus (Po4-) 2.5-4.5 mg/dL
Magnesium (Mg2+) 1.8-2.5 mEq/L
proximal convoluted tubule
reabsorption of sodium potassium calcium and glucose, uses active transport
thick descending
absorption of na through active transport but get water as well
thick ascending
sodium chloride and bicarb being reabsorbed
distal tubule
phos
collective tubule
selectively allow water reabsorption based on adh, it’s the last ditch effort to maintain ph. Bicarb and hydrogen and K+ reabsorbed
Antidiuretic Hormone
- Increases the permeability of collecting tubule cells to water.
- Increases water, but not electrolyte reabsorption
Renin
- Converts angiotensin into angiotensin I which is then converted to angiotensin II
- Angiotensin II causes vasoconstriction and the release of aldosterone (important for na+ reabsorption in the distal tubules)
Aldosterone
- Promotes sodium reabsorption in the distal tubules
- Leads to increase water absorption
- Urinalysis
- Volume
- pH
- Protein
- Glucose/ketones
- Sediment
- Osmolality
- Sodium concentration
- Fractional Excretion of Sodium Test
What do each of these tests help identify
- Urinalysis
- Volume: less than 30, they are anuric
- pH: between 5 & 6.5. High = UTI. Low= acidodic states in the body
- Protein: never normal in urine. Check it with 24 hour urine collection
- Glucose/ketones: present when high glucose serum. Spillage above 200. Ketones present for fat metabolism
- Sediment: some time of cellular breakdown. Not normal. Good indicator for pre-renal failure
- Osmolality: 300-900. Specific gravity 1.001-1.022. If specific gravity high= sediment and renal damage.
- Sodium concentration: less than 10 is normal. If elevated, think of renal failure.
- *Fractional Excretion of Sodium Test*: compares serum sodium to urine sodium. Greater than 1%= intrarenal failure. 1% or less= pre-renal failure
Blood Studies for renal failure
Creatinine/ Creatinine Clearance
Estimated Creatinine Clearance formula
(140-age) X weight in kg/ (Plasma Creatinine mg/dL) X 72
Blood Urea Nitrogen: increases in renal failure, GI bleed, dehydration, trauma.
8-20 mg/dL (normal)
BUN/Creatinine ratio:
Based on serum creatinine
BUN:Creatinine – 10:1 (normal)
- when ratio goes down: liver failure, fluid volume overload,
- ratio up: dehydration, catabolic states or high protein diets
Osmolality: Up= kidneys not filtering properly
Normally 280-290
Uric Acid: elevated=kidneys not filtering uric acid properly
2-8.5 mg/dL
Hemoglobin & Hematocrit: decrease shows renal problems
Men 13.5-17.5 g/dL & 40-52%
Women 12-16 g/dL & 37-48%
Increased Anion Gap
Increased anions: much more common than decreased
Metabolic acidosis
Lactic acidosis
Ketoacidosis
Uremic acidosis
Ingestion of chemicals
Ethylene glycol
Methanol
Paraldehyde
Salicylates
Penicillin
Carbenicillin
Hyperalbuminemia
Decreased cations
Hypokalemia
Hypocalcemia
Hypomagnesemia
Anion Gap
Provides insight into the chemical neutrality of the blood
Na+ + (Cl- + HCO3-)
Normal is 12 mEq/L
Decreased Anion gap
Decreased Anion Gap
- I_ncreased cations_: Hypercalcemia, Hyperkalemia, Hypermagnesemia
- Lithium
- Myeloma
-
Decreased anions: hypoalbuminemia
*
Risk Factors for Excessive Fluid Loss
- Fever
- Environmental
- Hyperventilation
- Gastrointestinal loss
- Third Spacing
- Burns
- Renal Loss
- Surgical Blood Loss
1 liter of fluid =?kgs
1 liter of fluid = 1kg
Oliguria in a child
an output of less than 0.5 mL/Kg/hour
Acute Kidney Injury
- Classified as: Sudden loss of renal function resulting in impairment in fluid/ electrolyte and/or acid-base balance.
- 5% of all hospitalized patients develop AKI
- 20% of ICU patients develop AKIMortality associated with ARF remains 40-70%
- Of those who survive, 45% will have return of renal function
Types of kidney failure
- Pre-Renal: occurs before you get to the kidneys. Hypovolemia, blockages. Can lead to Intra-Renal.
- Intra-Renal: Occurs inside the kidney. Metabolites collecting and causing damage, trauma, toxicity, etc.
- Post-Renal: Involves ureters, prostate, and bladder.
Risk Factors for AKI/ ARF
- Diabetes (Type I or II)
- Chronic renal insufficiency
- Heart disease (heart failure)
- Hypertension
- Advanced age
- Sepsis
Contributing Factors in the Development of AKI/ARF Pre-renal
- Hypotention
- Hypovolemia
- Decrease CO
- Dehydration
- Vascular Disease
- Renal Vein Thrombosis
- DM