CMS III Final: Nephro

what is the difference between reabsorption, secretion, and excretion?

reabsorption = absorbed back into the blood

secretion = released into filtrate

excretion = urine outside body

which structure in the juxtaglomerular apparatus (JGA) senses solute load?

macula densa → releases renin

what converts angiotensinogen to angiotensin 1?

renin

ACE converts angiotensin 1 to 2

what is the best index for kidney function?

GFR

> 90 = stage 1

60-89 = stage 2

30-59 = stage 3

15-29 = stage 4

< 15 = stage 5

which imaging modality is best for evaluation of solid/cystic lesions in the kidney or peritoneal space?

renal CT → definitive role in staging renal cancer and imaging following trauma

use renal US first

what may cause BUN to increase?

- acute/chronic RF

- urinary obstruction

- dehydration

- reduced perfusion (CHF, hypovolemia)

- increased protein

- accelerated catabolism

- steroids

- tetracyclines

what may cause BUN to decrease?

- overhydration

- increased perfusion (preg, SIADH)

- restriction of protein/malnutrition

- liver dz

an osmolality gap over ____ suggests hyperosomolar state

10***

2 x serum Na + BUN/2.8 + glucose/18 ***

which hormone retains sodium and water but causes K+ loss?

aldosterone

which dipstick finding is useful for determining hydrating status and concentrating ability of the kidneys?

specific gravity →correlates with osmolality

what is often the 1st indication of renal dz?

proteinuria → dipstick is most sensitive to albumin

when may there be a false positive urine ketone?

fasting

postexercise

pregnancy

which UA finding is assoc. with intraparenchymal bleeding?

RBC casts → HALLMARK of glomerulonephritis

which UA finding is assoc. with pyelonephritis?

WBC casts*** → upper UTI

what is an infection of the renal parenchyma and renal pelvis that ascends from the lower urinary tract?

pyelonephritis → E. coli

what is the outpatient tx for pyelonephritis?

FQs

what are the causes of hypovolemic hyponatremia?

- fluid loss (GI, burns)

- hypotonic fluid replacement

- thiazide diuretics (inc. Na, dec. K+)

- K+ depletion in cells (Na+ moves into cells)

- aldosterone deficiency (Inc. Na+ excretion and water loss)

what are the causes of euvolemic hyponatremia?

edema is NOT present!

- SIADH

- polydipsia

- diuretics

- hypothyroidism (low CO triggers ADH secretion)

- severe HYPERglycemia (polyuria)

what are the causes of hypervolemic hyponatremia?

edema is present!

- CHF

- cirrhosis

- overhydration

- nephrOtic syndrome

- renal failure (can't get rid of water)

what are the causes of redistributive hyponatremia?

TBW and sodium is unchanged

hyperglycemia or admin of mannitol

what is the MCC of hypernatremia? what are the causes of it?

hypOvolemic hypernatremia:

- dehydration

- vomiting or diarrhea

what are the causes of euvolemic hypernatremia?

- insensible losses (skin/stool/lung loss)

- polyuria

- DI

what are the causes of hypervolemic hypernatremia?

- hypertonic saline/bicarb tx

- hyperaldosteronism

- cushing's

when is pseudohyponatremia seen?

hypertriglyceridemia**

multiple myeloma

what is the sweet 16 rule for pseudohyponatremia?***

correcting sodium for hyperglycemia → add 1.6 to sodium for ever 100 mg of glucose over 100

ex: Na 126 and glucose 600 → (600 - 100 = 500) 500/100 = 5, 5x1.6 = 8 + 126 → 134 is true sodium

what are causes for hypokalemia?

- decreased dietary intake

- diuretics → MC!!

- insulin

- alkalosis

- hypomagnesemia

- hyperaldosteronism

what are causes of hyperkalemia?

- excess intake

- metabolic acidosis ***!!!!!

- insulin deficiency

- drugs

- ACEIs

- K+ sparing diuretics

- decreased excretion (RF, hypoaldosteronism)

hypo or hyper kalemia causes cardiac arrhythmias/arrest and peaked T waves?

hyperkalemia

which dx is characterized by increased thirst, hypernatremia, and loss of large volumes of urine?

DI → loss of ADH production/function

which drugs can cause SIADH?

lithium

SSRIs

ecstasy

cytoxan

narcotics

which drug can cause nephrogenic DI?

lithium***

which renal dz can be caused by secretion of small cell lung cancer (AKA oat cell)?

SIADH***

which dx is characterized by pathologic water retention and hyponatremia with concentrated urine?

SIADH

what is a serious complication of rapid correction of hyponatremia using hypertonic saline?

central pontine myelinolysis

when is hypertonic saline indicated for hyponatremia?

seizures

coma

focal findings

neuro symptoms***

what are the indications for normal saline?***

- ECF volume depletion

- post op fluid management

- shock

- hemorrhage

- burns

- blood transfusion

what are the indications for hypotonic saline?

- hypertonic pt

- hyperosmolar state d/t hyperglycemia

- hypernatremia w ECF volume depletion

why can't pure water be given IV?

causes hemolysis → use D5W for pts with normal BP***

what are the causes of respiratory acidosis?

hypoventilation

PNA

HF (shunting)

coma

what is the compensation for respiratory acidosis?

kidney retain bicarb (slow process)

what are the causes of respiratory alkalosis?

hyperventilation → panic attacks, anxiety → blowing off too much CO2

what is the compensation of respiratory alkalosis?

kidney excretes excess bicarb, retains H+

what are causes of HAGMA?

MUDPILES***

Methanol

Uremia

DKA

Paraldehyde

Isoniazid, iron

Lactic acidosis

Ethylene glycol

Salicylates

what are causes of NAGMA?

HARDUP (loss of HCO3 and/or gain of Cl)***

Renal tubular acidosis

Diarrhea

what is the compensation for metabolic acidosis?

lung hyperventilate →get rid of CO2 and raise bicarb

what are the causes of metabolic alkalosis?

vomiting

gastric suction (NG tube)

antacids, diuretics

what is the compensation for metabolic alkalosis?

lung hypoventilation → retain CO2 to increase PaCO2

how do you determine if there is compensation for metabolic acidosis?

Winter's formula***

PCO2 = (1.5 x HCO3) + 8 +/- 2

if value falls in range → compensatory

what is the MC form of acute glomerulonephritis (GN)?

IgA nephropathy AKA Berger's dz → assoc. with URI/flu-like illness

pt presents with dark cola colored urine, decreased urine volume, and periorbital edema. what is the tx?

nephritic syndrome → steroids for inflam, reduce BP with water/Na+ restriciton/diuretics/diaysis

what are the s/sx of nephritic syndrome?

triggered by immune response (think infection)

- dark cola urine

- decrease urine volume

- edema (scrotal/periorbital)

- HTN d/t fluid overload

- Dec. GFR, RBC casts

what is the standard for dx of IgA nephropathy?

renal Bx → diffuse mesangial IgA deposits and proliferation

what are the sx of IgA nephropathy?

- painless hematuria***

- inc. serum IgA

which dx is likely when > 50% of glomeruli contain cresents?

rapidly progressive GN (RPGN) → crescents are in response to glomerular rupture d/t severe injury

which dx involves GN plus pulm hemorrhage that is mediated by anti-GBM antibodies?***

goodpasture's syndrome

what are the s/sx of Goodpasture's syndrome?

hemoptysis

tachypnea

malaise

anorexia

HA

may have preceding URI

HTN and edema (components of nephritis syndrome)

what is the tx for Goodpasture's?

high dose steroids and immunosuppressive tx

what is the confirmatory finding for Goodpasture's?

circulating anti-GBM abs**

other findings:

bx shows crescents/adhesions, inflam infiltration

CXR shows pulm infiltrates d/t pulm hemorrhage

what is the hallmark sign of nephrotic syndrome?

peripheral edema

what are the 4 MCC of nephrotic syndrome?***

1. minimal change dz

2. membranous nephropathy

3. focal glomerular sclerosis

4. membranoproliferative GN

common in kids and adults

what are the s/sx of nephrotic syndrome?

-Edema: periorbital, peripheral, generalized, anasarca; worse in morning

- HEAVY proteinuria >3.5/day

- dyspnea (d/t pulm edema, pleural effusion)

- hypoalbuminemia (causes edema)

- VTE (severe cases)

- hyperlipidemia

NO HTN OR HEMATURIA

what is the most specific lab finding in nephrotic syndrome?

lipiduria → d/t hypercholesterolemia

maltese cross!

why is VTE a risk in severe nephrotic syndrome?

albumin <2 = hypercoagulable

what is the tx for nephrotic syndrome?

1. proteinuria = ACE/ARB

2. edema = salt restriction/diuretic

3. hyperlipidemia = diet/exercise, statin

what is the MCC of primary nephrotic syndrome in children?

minimal change disease AKA lipoid nephrosis

disappearance of proteinuria with prednisone is considered diagnostic for which dx?

minimal change disease → same sx as nephrotic syndrome

tx with prednisone!!

what is the MCC of primary nephrotic syndrome in adults?

membranous nephropathy → assoc. with occult carcinoma and thromboembolism***

in which nephrotic syndrome is there a high incidence of renal vein thrombosis and occult neoplasms?***

membranous nephropathy

which conditions does focal glomerular sclerosis occur secondarily to?

heroin abuse

morbid obesity

HIV infection

NSAIDs

Folks (focal sclerosis) with HIV do Heroin

what do most pts with focal glomerular sclerosis present with?

microscopic hematuria

many also have HTN

what is the tx for focal glomerular sclerosis?

long term oral steroids

which dx is seen in lupus nephritis patients?

membranoproliferative GN → most pts are <30 yrs old

tx with steroids and antiplatelets

which lab test can be used for muscular/obese people to estimate their creatinine?***

cystatin C

which endocrine dx can cause CKI?

hyperparathyroidism**

which acid base disorder is seen in aspirin overdose?***

met acidosis PLUS resp alkalosis

where are glucose and bicarb reabsorbed?

PCT

what is the definitive test for dx of interstitial nephritis?

biopsy***

what is seen in postinfectious GN?***

- oliguria

- edema

- cola colored urine

- RBC casts, proteinuria <3.5

- 10-14 days after strep

what is the MC UTI organism in sexually active female adolescents?

staph saprophyticus ***

E. coli is MC in general → ascending route of infection

how are Tamm-Horsfall glycoproteins preventative of UTIs?***

inhibit bacterial adherence

excreted with excessive exercise!!!!***

which dx shows dysmorphic RBCs on UA?

GN!!**

what is the MC type of renal cancer?

renal cell carcinoma (RCC) → arise from PCT/small tubules of nephron

what should you do if your pt with RCC has metastatic disease?

refer for dialysis ***

what are the risk factors of RCC?

- SMOKING!!!

- obesity

- analegics

- FHx

where are H+ ions secreted in the nephron?

cortical collecting duct***

where do thiazide diuretics work?

distal convoluted tubule***

what are the causes of pre-renal azotemia?

- intravascular volume loss (ECF)

- change in vascular resistance

- low CO

hemorrhage, GI loss, dehydration, excessive diuresis, pancreatitis, burns, trauma, peritonitis

what do labs show in pre-renal azotemia?

BUN:Cr > 20:1

urine Na+ < 20 (low)

FEna <1 (low)

hyaline casts

what is the MCC of renal (intrinsic) AKI?**

ATN → 2 major causes = ischemia and nephrotoxin exposure

what are the exogenous nephrotoxins that cause intrinsic azotemia?

- aminoglycosides !!

- vanco, cephalosporins

- contrast media

- cyclosporin

- antineoplastics (cisplatin)

- heavy metals

what are the endogenous nephrotoxins that cause intrinsic azotemia?

- heme products (Myoglobin, Hgb)

- uric acid

- paraproteins (Bence jones)

EXogenous MC than ENdogenous

what are the s/sx of ATN intrinsic azotemia?

- generalized swelling

- n/v

- oliguria

- decreased LOC

- anorexia

- muscle weakness

- pulm edema

what are the causes of postrenal azotemia?

obstruction → BPH, cancer, neurogenic bladder, clots, stones

what do labs show in postrenal azotemia?

- BUN:Cr > 20:1

- urine Na+ > 20 (high!!)

- FE na >1 (high)

tx by relieving obstruction!!

taking anticholinergic drugs is a risk of developing which type of azotemia?

post renal → risk for urinary retention

what is the MC indicator for CKI? When should you refer to nephro?

BUN and SCr (best is GFR)

refer to nephro at stage 3 (GFR <30)

which acid base disorder is MC in CKI?

metabolic acidosis

which type of renal stone is radiolucent?***

uric acid

which type of kidney stone is assoc. with proteus mirabilis UTI?

struvite

which stones are radioopaque?

Calcium Oxalate (MC), Calcium Phosphate, and Struvite