Week 5: Acute and Chronic Kidney Disease Flashcards
what is the function of the glomerulus and tubular system? what is essential for reabsorption to happen?
glomerulus
- selective filtration of water & solutes from blood
- filtration of blood: 125mL/min but only 1mL/min is excreted as urine
tubular system
- reabsorption of essential minerals; excretion of non-essential ones
- dense capillary network needed for reabsorption ability
what is the nephron’s function and parts of the nephron w/functions?
Functional unit of the kidney working for electrolyte balance and blood pressure
Glomerulus
- capillary network allowing for filtration
Bowman’s capsule
- part containing the glomerulus
Proximal tubule
- reabsorption of 80% electrolytes and water
- majority of absorption occurs here
Loop of henle
- concentration and conservation of water
- ascending limb: Na and Cl
- descending limb: water
Distal tubule
- permeable/impermeable to water and solutes so we can have final concentration
- ADH influences permeability of nephrons (high level = more water reabsorption)
- acid-base balance impact
Collecting duct
- reabsorption of water with ADH
- everything is getting ready for excretion
vascular anatomy of the kidneys: cardiac output
- highly vascular
- receive up to 20% of CO
- 1L to 1.2L/min of blood flow
vascular anatomy of kidneys: renal artery
- divides into arterial branches that become progressively smaller vessels ending with the afferent arterioles
arterial branches:
- afferent arterioles: single afferent supplies blood to each glomerulus
- efferent arterioles: blood exits glomerulus
3 processes involved in urine formation
- glomerular filtration
- tubular reabsorption
- tubular secretion
functions of the kidneys (6)
- elimination of metabolic wastes
- blood pressure regulation: RAAS system, increase BP to have better kidney perfusion. Increase aldosterone also increases BP
- erythrocyte production: production of RBC in bone marrow, renal failure can cause anemia
- Vit D activation: needed for calcium uptake in GI. If GFR > 40, we cannot activate Vit D. We give Calcitriol if pt cannot activate.
- Prostaglandin synthesis: simulate renin production, RAAS system, and impact local constriction/dilation of muscle impacting glomerulus pressure
- Acid-base balance: ex. resp distress causing resp acidosis (increase CO2 increase acid levels), so kidneys kick in to fix it OR they become compromised
Chronic kidney disease characteristics
kidney damage or decreased function for a period greater than 3 months
- decreased function: GFR <60mL/min/1.73 m2
- kidney damage: urinary albumin excretion of ≥30mg/day or equivalent
- develops slowly (adaptive hyperfiltration, increased pressure)
- GFR accompanied by urine sediment or abnormal imaging test results
- kidney biopsy with abnormalities
Acute kidney injury characteristics
- sudden decline in renal function (hours/days)
- increased BUN and CR
- oliguria <400ml/24hr
- hyperkalemia and Na retention
What is important in a history assessment regarding kidney damage? (7) - C P H E I S R
- complaints: onset, location, duration
- predisposing factors: medicines (OTC, antihypertensives), recent infections requiring antibiotic therapy, diagnostics using radiopaque contrast
- recent history: SOB, change in cognition, rapid fluid volume gain, weight gain 2lb+/day, nutritional-metabolic pattern
- signs that suggest extracellular fluid depletion: thirst, decreased skin turgor, lethargy
- Signs implying intravascular fluid volume overload: pulmonary congestion, increasing heart failure, rising BP
- past kidney studies: imaging, biopsy
- risk factors: fam history, hypertension, diabetes mellitus, prior acute kidney failure
what are the 4 ongoing assessments
- weight monitoring
- daily, fluctuations over 1-2lb/day indicates fluid gains and losses
- consider dry weight (wt b4 retention) - intake and output monitoring
- identify +/- fluid balances
- assess hourly in some cases - neurological findings
- LOC changes due to inadequate perfusion, increase in toxins - Hemodynamic monitoring
- assesses volume depletion and volume overload
- heart can be tachycardic to accomodate for inadequate perfusion (↑SNS stimulation)
what are the 11 lab assessment serum components
- blood urea nitrogen (BUN)
- Creatinine
- estimated glomerular filtration rate
- hemoglobin and hematocrit
- albumin
- acidosis
- electrolytes
- BUN to creatinine ratio
- creatinine clearance
- osmolality
- blood gases - anion gap
Lab assessment: blood urea nitrogen (BUN)
- normal range
- considerations
- 3.6-7.1
- by product of protein and amino acid metabolism
- elevated with GFR ↓and resulting ↓ in urea excretion
- ↓ with volume overload, liver damage, severe malnutrition, use of phenothiazines, or pregnancy
Lab assessment: Creatinine
- normal range
- considerations
male: 53-106 mmol/L
female: 44-97 mmol/L
- byproduct of muscle and normal cell metabolism
- completely excreted when kidney function is normal
- even small increases represent significant decrease in GFR
Lab assessment: GFR
- normal range
- considerations
90-120 mL/min/2.73 m2
- based on creatinine level, age, sex
- defined: amount of blood filtered by glomeruli in a given time
- great indicator of renal function
Lab assessment: hemoglobin and hematocrit
- considerations
- indicates increases/decreases in intravascular fluid volume
- increase in hematocrit indicated fluid volume deficit resulting in hemoconcentration
- decrease in hematocrit indicates fluid volume excess because of dilutional effect of extra fluid load
Lab assessment: albumin
- considerations
- responsible for colloid osmotic pressure maintenance
- decreases levels result in fluid shift from plasma to interstitium, creating peripheral edema
Lab assessment: acidosis
- considerations
- pH < 7.35
- severe acute kidney insult
- metabolic acidosis occurs as a result of accumulation of un-excreted waste products
Lab assessment: electrolytes
- considerations
imbalances indicating renal failure
- no excretion or retainment
- risk for hyperkalemia which impacts cardiac function
Lab assessment: BUN to creatinine ratio
- consideration
- BUN and CR levels elevated and maintained at 10:1, disorder is intrarenal or affecting tubules of kidneys
- > 10:1 cause is most likely prerenal
Lab assessment: creatinine clearance
- normal range
- considerations
85-135mL/min
- amount excreted in urine and amount in blood over 24h
- renal failure: ↓ in urine and ↑ in blood
Lab assessment: osmolality
- considerations
- elevated = hemoconcentration or dehydration
- decreased = hemodilution or volume overload
Lab assessment: blood gases - anion gap
- considerations
- increases level reflects overproduction or decreased excretion of acid products and indicated metabolic acidosis
- decreased anion gap indicates metabolic alkalosis
what do we look for in a urinalysis
- urine appearance
- urine pH
- urine specific gravity
- urine osmolality
- urine protein
- urine glucose
- urine ketones
- urine electrolytes
- urine sediment
- hematuria
what is a urine toxicology screen
urine drug screen (UDS)
- used to find cause of altered LOC
- detects alcohol, illegal drugs, prescription and nonprescription meds, other substances