Nephrology Flashcards
Bartter syndrome
Renal tubular salt wasting disorder in which the kidneys cannot reabsorb sodium and chloride in the thick ascending limb of the loop of Henle
Hypertrophy and hyperplasia of renal juxtaglomerular apparatus
Decreased Na, K, Cl
Increased HCO3, Calcium
Nephrocalcinosis
Severe polyhydramnios
Looks like being on lasix
Calcitonin
Secretion: parafollicular/C cells of thyroid in direct response to Ca levels
Inhibits osteoclasts bone resorption
Enhances renal Ca excretion
Modulates prolactin secretion
Vitamin D
Crosses placenta (vit d and 25 vit d)
1,25- active form- does NOT cross placenta
Placenta and kidney make 1,25
Calcium control in fetus versus neonate
Fetus: high calcitonin, low PTH
Neonate: PTH takes control after birth, stimulated by fall of calcium after birth- nadir 24-48 hrs
Vitamin D INDEPENDENT mechanism
Normal calcium levels
Ionized: 1.1-1.3
Serum: 8.8- (10-12)
Hypocalcemia <7 IF normal albumin
Total calcium falls 0.8mg/dL for every 1g/dL decrease in serum albumin
contraction alkalosis from diuretics
- Reduction in ECF volume
- Increase Na+ reabsorption
- Increased renal K+ and H+ secretion
- HCO3- reabsorption increases to maintain neutrality
- Volume depletion
- Stimulated renin
- Increases aldosterone
- Promotes further Na+ reabsorption and K+/H+ secretion
acidosis effect
for every 0.1-unit reduction in arterial pH, thre is approxx 0.6mEq/L increase in plasma K+
How to treat hyperkalemia
- REMOVE ALL EXOGENOUS K SOURCES
- 10% calcium gluconate
- glucose: D10W + insulin (increases intracellular update of K+ by direct stimulation of Na/K ATPase)
- furosemide
- NaHCO3
- Kayexalate
acidosis effect on K
alkalosis effect on K
hyperkalemia (0.1 dec ph = 0.6 inc K)
hypokalemia
major extracellular buffer system
CO2 crosses into brain –> decreases pH –> stimulates chemoreceptors –> increases respiratory drive –> eliminating CO2
H+ crosese cell membrane to reach buffer systems using 3 methods
1. Na+/H+
2. K+/H+
3. HCO3-/Cl
intracellular buffer systems
bone apatite
hemoglobin
organic phosphates
reabsorption of HCO3-
60-80% occurs in PROXIMAL TUBULE
anion gap metabolic acidosis
hypochloremic metabolic alkalosis
PYLORIC STENOSIS
cystic fibrosis
Bartter syndrome
diuretic therapy
type 1 RTA
distal or classic RTA
cannot secrete H+ in distal tubule
renal bicarb threshold is normal
urine pH > 6.2 –> CANNOT acidify urine
increased risk of renal stones –> minimize calcium excretion in urine
treat with bicarb or citrate
type 2 RTA
proximal
proximal think preemie
decreased/absent proximal tubular HCO3- reabsorption
reduced renal bicarb reabsorption threshold
normal distal acidification
large urine loses of bicarb–> urine pH < 5.3
normal urine concentrating ability
substantial K+ losses (instead of H+)
treat with bicarb or citrate, +/- phos, vitamin d
how does RTA cause growth issues?
blunts growth hormone axis and release
when does urine production occur?
10-12 weeks
major constituent of amniotic fluid production, increases with age
renal blood flow
25 weeks: 20ml/min
full term: 60ml/min
renal blood flow only accounts for 2-3% of cardiac output in utero
FENa
< 1% normal
1-2.5% = pre-renal
> 3% = intrinsic renal failure
Nephrogenesis
deep nephrons formed first
number increases until 34-35 wks then size of nephrons increases
at birth, juxtaglomerular nephrons more mature than superficial nephrons
FGR reduces number of nephrons
renal concentrating ability
fetal urine is hypotonic
osmolality increases with gestational age
max osm:
premature 500mOsm/L
term 800mOsm/L
adult ability reached at 6-12 mo: 1200osm/kg
why do preemies have a reduced concentrating ability?
tubule insensitivity to vaspressin
short loop of Henle
low osmolality of medullary interstitium –> limited Na+ reabsorption in thick ascending limb
low serum urea
renin-angiotensin system
what stimulated renin release?
decreased renal perfusion–> hypotension, volume depletion
increased sympathetic activity
where does ACE come from?
angiotensin converting enzyme
lung endothelium
what does aldosterone do to the kidney?
increase Na+ reabsorption
increase Cl- passively
increase K+ secretion
increase H+ secretion
what does angiotensin II do?
increasea Na+, H2O reabsorption by direct tubular stimulation
arteriolar vasoconstriction
stimulates release of ADH
stimulates release of aldosterone
activates vitamin D by PTH
activates erythropoietin
pseudohypoaldosteronism
XR
unresponsiveness of renal tubule to aldosterone
Labs: decreased Na, increased K, metabolic acidosis, increased aldosterone, increased renin
Presentation:
prenatal: increased UOP, polyhydramnios
2-3 mo: dec feeding, vomiting, FTT
rule out CAH
give Na/Cl, indomethacin to reduce UOP
causes of increased BUN
dehydration
increased protein intake
hypercatabolic states/hypoxia
sequestered blood
tissue breakdown
definition of hematuria
> 5 RBCs per HPF
cause of sediments:
1. leukocyturia
2. RBC casts
3. WBC casts
4. epithelial, granular casts
5. hyaline casts
- UTI, obstructive uropathy, glomerulonephritis
- glomerular injury
- infection, renatl interstitial/tubular injury
- dehydration, renal interstitial/tubular injury
- severe proteinuria, dehydration
lenth of kidneys on US is proportional to what?
gestational age in weeks
most common renal anomalies
horshoe kidney (Turner Syndrome)
unilateral renal agenesis (L>R)
pelvic kidney (L>R)
congenital nephrotic syndrome
PROTEINURIA, hypoproteinemia, hyperlipidemia, edema
Finnish: Chr 19- NPHS1 (nephrin), AR;
- 90% sxs by 1 mo, dx by 3 mo
- large placenta, increased alpha-fetaprotein, ? hydrops
- SGA, premature
- complications: infection, thromboemboli –> urinary losses of IgG and coag proteins
Diffuse mesangial sclerosis:
later onse, normal placenta/alpha-feto/BW
- rapidly develop renal insufficiency
- early-onset hypertension
renal agenesis
1/10,000
recurrent risk: 3-5%
40% stillborn or die shortly after birth
Associations:
- oligohydramnios sequence
- pulmonary hypoplasia
- Potter’s syndrome
- single umbilical artery
muticystic dysplastic kidney
MCDK
M>F
L>R
sporadic
cysts: unilateral > bilateral, multiple, non-communicating, “grape-like” clusters
GU anomalies (90%)
bilateral disease in neonatal period- severe clinical presentation- oligo, life-threatening secondary complications
ARPKD
INFANTILE!
M=F
PKHD1 - encodes fibrocystin/polyductin
CILIA related disorder
Neonates: kidney > liver
Child: liver > kidney
severe HTN - ACEi or loop diuretics
INCREASED RISK: hepatic fibrosis, biliary dysgenesis, portal hypertension
Fanconi syndrome
RARE, AD, sporadic
proximal tubule dysfunction leading to excess urinary losses of AA, glucose, phos, bicarb
polyuria with increased risk for dehydration, rickets
labs: dec phos/TRP, metabolic acidosis, hypokalemia, normal glomerular function
Lowe Syndrome
oculocerebrorenal syndrome
XR
gene defect leads to an enzyme deficiency –> disrupts Golgi apparatus which helps regulate specific cell lines
exstrophy of cloaca sequence
primary defect of early mesoderm
leads of failure of cloacal septation and the ureters/ileum/rudimentary hindgut connected to common cloaca
associated with omphalocele
Exstrophy of bladder sequence
primary defect of infraumbilical mesoderm at 6-7 weeks
risks for HTN
BPD
central lines
postnatal acute renal failure
which anti-hypertensive medication is contraindicated in neonates?
verapamil
most common nephrotoxic drugs
acyclovir
aminoglycosides
amphotericin B
vancomycin
first choice for dialysis in a neonate
peritoneal
indications for dialysis in neonate
hyperkalemia
hyponatremia with symptomatic volume overload
hyperphosphatemia
metabolic acidosis
hypocalcemia
uremic symptoms
inability to provide adequate nutrition due to need for fluid restriction
GFR depends on?
- flow in the afferent arteriole
- transcapillary hydraulic pressure
- colloid osmotic pressure
- permeability of the glomerular capillaries
most common cause of acute renal failure in neonate
HIE
most common cause of prenatal hydronephrosis
no specific cause
cause of renal dysplasia
no interaction of the ureteric bud with undifferentiated mesoderm
cause of renal agenesis
ureteric bud fails to develop
plasma osmolality
FeNa
TRP
Tubular Reabsorption of Phosphate
sodium deficit
congenital nephrotic syndrome
large hypoechoic kidneys on prenatal US
elevated maternal serum AND amniotic fluid alpha fetoprotein
presentation: edema, wide cranial sutures, large open fontanelle, premature, SGA
UA = proteinuria
Dx with genetic testing: NPHS1/S2, WT1, PLCE1
