Nephrology/Urology Flashcards
(171 cards)
Most common cause of nephrotic syndrome in adults
Membranous nephropathy
Signs of a CHRONIC kidney problem
High Cr, high BUN
Low albumin
Kidney should not be dumping any albumin into urine - if albumin is low - it is a chronic problem - either from kidney dumping or liver not synthesizing
Kidney functions
A WET BED
Acid-base balance
Water reabsorption/balance
Electrolyte balance
Toxin filtering/removal
Blood pressure control (RAAS)
Erythropoiesis (produces EPO)
D - Vitamin D activation
What is Cr? Why is it used as a marker for kidney function?
Creatinine is a breakdown product of muscle
It is the only substance 100% filtered from our blood to our urine & 100% secreted out (not reabsorbed at all) so it is a surrogate marker for how well the kidney is filtering the blood
A bump in Cr from 0.3 to 0.6 actually means you lost 50% of your filtration rate because the Cr doubled!
Therefore the creatinine clearance (CrCl) is used estimate the GFR
Why is metabolic acidosis common in chronic renal failure?
Beginning of CKD - kidney nephrons/tubules are damaged & the tubules are unable to secrete H+ as efficiently as before (remember we take in a high daily acid load that must be secreted!) - this is a non-anion gap metabolic acidosis
Then later on when urea starts building up we get an anion gap metabolic acidosis - kidneys can’t keep up excreting/getting rid of blood urea
Most common electrolyte abnormality & two main causes
Hyponatremia
Two causes:
SIADH –>
Hypo-osmolar (all pt’s who are underperfused ADH will be released - CHF, shock, MI etc) - also psychogenic polydipsia, beer potomania etc
Hyperglycemia (DKA)–>
Hyper-osmolar (pseudo-hyponatremia) - treat w/ insulin (check K+ first)
Management of hyponatremia caused by SIADH
Remember ALL patient’s who are hypo-perfused will have SIADH!!! (CHF, MI, SHOCK)
Tx = restrict water intake
Correct Na+ balance SLOWLY - 1-2mEq/hour then slower when sx improve
Goal is Na+ of 125-130
What happens if you correct a low sodium too fast? What are si/sx of that?
Central pontine myelinolysis
AKA iatrogenic cerebellar swelling = BRAIN HERNIATION = BAD NEWS!!!!
Two main causes of hypernatremia?
- Diabetes insipidus - central (low ADH level) vs nephrogenic (kidney insensitivity to ADH- THINK DRUGS!!!)
- Excess water loss (iatrogenic osmotic diuresis w/ mannitol etc)
Note that the main causes of hyper-Na+ has to do with water loss rather than Na+ gain…
What would a urine sample look like if someone was peeing out large amounts of urine due to DI? Treatment?
If central DI then will be peeing out large amounts of DILUTE urine (low specific gravity) that is FREE of glucose
Give synthetic ADH duh! AKA desmopressin (use pulse IV form to prevent tachyphylaxis)
What is the type of patient who is at highest risk for developing central DI?
Someone post-head trauma or post-op
AKA neurosurg floor!
Remember posterior pituitary normally releases ADH
Central D. insipidus = IN-sufficient ADH
Causes of nephrogenic DI
BFTP: Nephrogenic DI = body making ADH but kidney is insensitive to it!
Etiology:
LITHIUM !!!!!!
Amphotericin B
Acute tubular necrosis
Hyper-PTH
Hypercalcemia & hypokalemia
(usually use ions to concentrate urine)
CP DI
Polyuria
Polydipsia
Nocturia (may manifest as enuresis in children)
Hypernatremia
Dehydration, hypotension
Name the two disorders of the posterior pituitary that cause disruptions in sodium and water balance?
Central DI - INsipidus = INsufficient ADH - dec ADH production centrally - idiopathic = MC, HEAD trauma, post-op etc
SIADH - syndrome of INCREASED ADH - occurs in anyone volume-depleted - CHF, MI, etc
Treatment hypernatremia 2/2 central DI
SLOW correction:
Drink free water orally
Desmopressin (DDAVP)
Carbamazepine (has anti-diuretic activity)
IF SYMPTOMATIC –> hypotonic fluid (free water orally, 1/2 normal saline, D5W)
What is the next test you order or look at if someone is hyponatremic?
Serum osmolarity!
LOW serum osmomlarity = SIADH - perfusional problem from another cause (CHF, MI, infection etc) and body produces too much ADH to compensate = dilutes out the serum = low serum osmolarity
HIGH serum osmolarity = hyperosmolar hyponatremia - sounds weird right? It is…only causes is hyperglycemia
Urine osmolarity low or high in DI?
Specific gravity low or high in DI?
LOW urine osmolarity (dilute) < 200
LOW specific gravity < 1.005
Causes of hyperkalemia
Abnormal distribution:
No insulin in DM
Acidosis –> too much H+ - body pumps K+ out, H+ into cells to compensate
Impaired renal excretion:
GFR<5, oliguria - AKA acute (pre-renal, intrinsic, post-renal) & chronic renal failure
Drugs:
Spirinolactone, ACEI, Bactrim
Hemolysis, trauma, burns, surgery
Treatment of hyperkalemia
- Stabilize cardiac membrane potential (give 1 amp of CaCO3 or CaCl)
- Move K+ into cells (D50% & 10 units insulin, bicarb (if acidotic will drive K+ into cells too)
- Increase excretion (Loop diuretic, kayexalate)
NOTE - IF K+ 7.5 b/c missed 2 days dialysis (ESRD) then TX = DIALYSIS not the above… DUH
Causes of hypokalemia
Vomiting - lose K+ = metabolic alkalosis b/c K+moves out of cells, H+ goes into cells
Diuretic therapy (loop, thiazide)
Too much insulin - redistributed all the K+ into cells
What should you always check next when you see a low K_?
Check a MAGNESIUM LEVEL!!
If s. mg is low, K+ will not replete - oral replacement of Mg is best
Remember: Hypo-K+ and Hypo-Mg+ cause dig toxicity at therapeutic dig levels
MCC hypomagnesemia
Alcoholism
MCC hypermagnesemia
Chronic renal failure
remember that the Mg2+ does what the K+ does
Which treatment for constipation would you NOT want to give to a person with CKD, ESRD etc
Don’t give MG citrate!
**Contains magnesium!
Assume that anyone with CKD/ESRD has high Mg2+! Remember that Mg2+ kind of does what K+ does