Nephrology Lecture Flashcards
what is the term used for elevated nitrogen containing compounds (urea, creatinine) in the blood?
azotemia
what is the term for symptomatic azotemia? what type of acid/base disorder will these patients have?
uremia
metabolic acidosis
according to KDIGO guidelines, what are the criteria for defining acute kidney injury?
1) rise in creatinine greater than 0.3 mg/dL
2) decrease in UO to less than 3 mL/kg over 6 hours
what is the most common presentation of acute kidney injury? what are some other presentations?
frequently asymptomatic with NO visible signs
other: HTN, edema, decreased UO
what will labs look like in AKI?
albuminuria
increased BUN
hyperkalemia
hyponatremia
in general, what type of physiologic state causes prerenal azotemia?
hypovolemic states with decreased perfusion to the kidneys
can cause prolonged renal ischemia
which two chronic conditions cause prerenal azotemia?
CHF and hepatic failure (cirrhosis) due to third spacing and hypoperfusion
which two more acute conditions cause prerenal azotemia?
1) dehydration (inadequate PO intake, GI losses, diuretics)
2) sepsis
type 1 renal tubular acidosis occurs where in the renal tubules? what problem does it cause?
type 1 = distal
causes decreased tubular H+ excretion – hypokalemia
type 2 renal tubular acidosis occurs where in the renal tubules? what problem does it cause?
type 2 = proximal
causes decreased proximal HCO3 reabsorption and hypokalemia
type 4 renal tubular acidosis causes impaired ____ and ____ excretion
type 4 = impaired hydrogen and potassium excretion
an ______ deficiency, as seen in addison’s disease and DM, is likely to cause type 4 renal tubular acidosis
aldosterone deficiency
we need aldosterone to help us excrete potassium, without it we become hyperkalemic
glomerulonephritis, nephrosis, minimal change disease, and nephritis are all causes of what type of renal azotemia?
intrinsic acute kidney injury
he did a terrible job at explaining these. but flip the card for a brief explanation of
1) glomerulonephritis
2) interstitial nephritis
3) acute tubular necrosis
1) glomerulonephritis – see RBC casts and blood on urinalysis
2) interstitial nephritis – caused by nephrotoxic drugs (NSAIDS, lithium), INFECTION, etc. – see WBC casts on urinalysis
3) acute tubular necrosis – causes are prolonged ischemia, contrast reaction, sepsis – see muddy brown casts (or nothing) on urinalysis
what are a few causes of postrenal AKI azotemia?
urinary obstruction!
prostatism, bladder, pelvic or retroperitoneal tumors, calculi, urethral obstruction
why might a low hemoglobin/hematocrit indicate renal disease?
kidneys responsible for making erythropoietin for RBC stimulation
what are the two ways we can prevent AKI?
1) sustain renal perfusion (fluid balance, BP maintenance)
2) don’t clog the pipes (see next card)
how can you prevent AKI in the following situations?
1) about to give contrast dye to someone with weak kidneys
2) patient presents with hemolysis and/or rhabdomyolysis
1) aggressive IVF to limit contact w/ kidneys or avoid exposure if possible
2) aggressive IVF to protect kidneys
what is the MOST important component of diagnosing AKI?
identify the underlying cause
almost can ALWAYS reverse AKI in a normal healthy patient
if patient is developing profound hyperkalemia, what can we give?
kayexelate
what are the four MC etiologies of chronic kidney disease?
1) AKI
2) HTN
3) DM
4) vascular disease
microalbuminuria is defined as ____ albumin in the urine
30-300 mg/24 hour period
what levels indicate microalbuminuria on a spot urine albumin-to-creatinine ratio in men vs. women?
17-250 mg/g (men)
25-355 mg/g (women
anything lower = normal
anything higher = albuminuria
what are the 5 (technically 6) stages of kidney failure with their corresponding GFR?
1: GFR greater than 90 2 (mild): GFR 60-89 3 (mod): GFR 45-59 4 (mod): GFR 30-44 4 (sev): GFR 15-29 5 (ESRD): GFR less than 15
what does the diet of a CKD patient look like when being managed in the hospital?
low sodium, low protein, low potassium, low phosphate
what should we avoid in all patients being hospitalized for CKD?
NSAIDS, radiocontrast, other nephrotoxins
where is the only place that you can measure potassium levels?
extracellular fluid volume (ECFV)
adrenal insufficiency will cause which electrolyte disturbance?
hyperkalemia
insulin deficiency will cause which electrolyte disturbance?
hyperkalemia
need insulin to get K into cell
being on a beta blocker puts you at risk for developing which electrolyte disturbance?
hyperkalemia
they impeded K’s ability to get into cell
aldosterone antagonists (spironolactone) will cause which electrolyte disturbance?
hyperkalemia
what are 5 ways we treat hyperkalemia?
1) IVF if fluid depleted
2) kayexelate if not hypovolemic
3) limit potassium intake
4) insulin + dextrose (drive K into cells)
5) beta adrenergics (counteract BB effect)
being hypomagnesemic can put you at risk for developing what electrolyte disturbance?
hypokalemia
ALWAYS get Mg level in the face of hypokalemia
what two drugs can cause hypokalemia?
insulin
beta agonists
manifestations of hyperkalemia? (3)
1) weakness
2) paralysis
3) cardiac arrhythmias!! peaked T waves, widening PR, QRS, eventual PEA
manifestations of hypokalemia? (3)
1) weakness/rhabdomyolysis
2) glucose intolerance
3) cardiac arrhythmias (U waves after T waves)
treatment of hypokalemia?
1) potassium replacement
2) magnesium replacement
what are the two types of loss that can cause hypokalemia? examples of both?
GI losses: vomiting, diarrhea, laxatives, tube drainage
Renal losses: diuretics, hypomagnesemia, non-absorbable ions
____ is the primary extracellular cation
sodium
in general, what are the two major causes of hypernatremia?
1) extrarenal water loss
2) renal water losses
what are examples of extrarenal water loss leading to hypernatremia?
fever, sweating, diarrhea
mechanical ventilation
what are some examples of renal water loss leading to hypernatremia?
1) osmotic diuresis (DKA, mannitol, sodium)
2) diabetes insipidus
3) iatrogenic (1 amp of NaHCO3 has twice the concentration of 3 percent saline)
what is the difference between central and nephrogenic diabetes insipidus?
central: low ADH production
nephrogenic: unresponsive to ADH
both cause polyuria, polydipsia, and hypernatremia
if urine osmols are greater than 300, what is the likely culprit of the hypernatremia?
osmotic diuresis
if urine osmols are less than 150, what is the likely culprit of the hypernatremia?
diabetes insipidus
treatment for hypernatremia? what do we need to be cautious of?
1) NS initially if volume depleted
2) transition to 1/2 NS vs. D5Q
**avoid correction faster than 0.5 meq/L to avoid cerebral edema
does hyponatremia mean low salt in the blood?
NO
decreased sodium CONCENTRATION
more water with relation to sodium
hyponatremia is typically associated with elevated _____
ADH
hyperosmolar or normosmolar hyponatremia is caused by what?
elevated levels of another osmolyte (glucose in DKA, diabetes; elevated proteins, lipids)
-these osmolytes are pulling more water into the blood, causing a hyponatremia
hypoosmolar hyponatremia is caused by what?
too much ADH
what causes too much ADH to be released? (3)
1) increased serum osmolality (ie uncontrolled diabetes)
2) decreased circulating volume (hypotension)
3) inappropriate (SIADH)
which electrolyte disturbance will CHF, cirrhosis, or nephrotic syndrome cause?
hypERvolemic hyponatremia
- third spacing causes decreased effective circulating volume
- kidneys respond by turning on RAA (retaining more sodium) and rising ADH (even though there’s plenty of volume)
vomiting, diarrhea, and dehydration will cause what acid base disturbance (in terms of sodium)?
hypovolemic hyponatremia
extrarenal losses
salt-wasting nephropathies, thiazide diuretics, and primary adrenal insufficiency will cause what acid base disturbance (in terms of sodium)?
hypovolemic hyponatremia
renal losses
if urinalysis of your hypovolemic hyponatremic patient shows greater than 30 mmol of sodium per liter, where is the issue? renal or extra renal?
RENAL issue. the kidney is releasing salt inappropriately
extra-renal losses will have less than 30 mmol of sodium per liter in their urine, because their kidneys are working properly and can retain sodium
SIADH and psychogenic polydipsia are causes of which type of electrolyte disturbance (in terms of sodium)?
euvolemic hyponatremia
what will urine osmols look like in euvolemic hyponatremia due to SIADH vs. psychogenic polydipsia?
urOsm greater than 100 in SIADH (you are reabsorbing so much water that the urine is very concentrated)
urOsm less than 100 is psychogenic polydipsia (kidney’s can’t keep up, very dilutee urine)
what will urine sodium of a euvolemic hyponatremia look like?
greater than 30 Una
RAA is NOT engaged (we have plenty of fluid) and sodium is being excreted
pain, volume depletion (followed by LR or hypotonic fluids), trauma, medications (SSRIs, thiazideS), neoplasms, severe nausea, and neuropsychiatric meds can all cause ____ to elevate
ADH
generally, how do we treat hyponatremia?
its an excess of water, but we treat it like a deficiency of salt
give IVF – percent saline depends on UrOsm
give loop diuretic (get excess water off)
fluid restrict
increase solute intake
ADH receptor antagonist
how much do we want to see our sodium rise when treating hyponatremia in a 24 hour period? what number must we not exceed in 48 hours?
no more than 10 mEq/L in first 24 hours
no more than 18 mEq/L in 47 hours
if our patient has chronic symptomatic hyponatremia, how do we manage? what do we worry about?
risk of osmotic demyelination syndrome if corrected too rapidly
may use brief stint of 3 percent saline – ALWAYS consult nephrology
under which 3 conditions should you discontinue NaCl administration via IVF for hyponatremia?
1) serum Na starts to rise
2) urine Osm falls
3) symptoms resolve
how do we treat hypovolemic hyponatremia?
NaCl, but usually asymptomatic
if you are in metabolic acidosis, will you be hyperkalemic or hypokalemic?
hyperkalemic
