Renal - First Aid Flashcards
Pronephros
week 4 kidney then degenerates
Mesonephros
functions as interim kidney for 1st trimester and later contributes to the male genital system
Metanephros
permanent; first appears in the 5th week of gestation
Ureteric bud
derived from the caudal end of the mesonephric duct; gives rise to the ureter, pelvises, calyces and collecting ducts; fully canalized by 10th week
Metanephric mesenchyme
ureteric bud interacts with this tissue inducing differentiation and formation of the glomerulus through to the distal convoluted tubule
The ureteropelvic junction is the…
last area to canalize and the most common site of obstruction in the fetus.
Potter Sequence is…
oligohydramnios leading to compression of the developing fetus leading to limb deformities and facial anomalies (low set ears and retrognathia) and compression of the chest leading to pulmonary hypoplasia.
Causes of Potter sequence include…
ARPKD, posterior urethral valves and bilateral renal agenesis. (babies who can’t Pee develop Potter)
POTTER syndrome is associated with:
Pulmonary hypoplasia Oligohydramnios (trigger) Twisted face Twisted skin Extremity defects Renal failure (in utero)
Horseshoe kidney
the inferior poles of both kidneys fuse and as they ascend from the pelvis during fetal development, they get trapped under the inferior mesenteric artery and remain low in the abdomen
Horseshoe kidneys have increased risk for…
ureteropelvic junction obstruction, hydronephrosis, renal stones and renal cancer (Wilms tumor).
Horseshoe kidneys are associated with…
Turner syndrome.
Multicystic dysplastic kidney is due to….
abnormal interaction between the ureteric bud and metanephric mesenchyme. This leads to a nonfunctional kidney consisting of cysts and CT.
If multicystic dysplastic kidney is unilateral (most common), then it is generally…
asymptomatic with compensatory hypertrophy of the contralateral kidney.
The kidney taken for donor transplantation is…
the left one becasue it has a longer renal vein.
The ureters pass….
under the uterine artery and under the ductus deferens.
The ureters may be damaged by gynecologic procedures involving…
ligation of the uterine vessels leading to ureteral obstruction or leak.
Plasma volume is measured by…
radiolabeled albumin.
Extracellular volume is measured by…
inulin.
Plasma osmolarity =
290 mOsm/L.
The glomerular filtration barrier is composed of…
- Fenestrated capillary endothelium (size barrier) 2. Fused basement membrane with heparan sulfate (negative charge barrier) 3. Epithelial layer consisting of podocyte foot processes
The charge barrier of the glomerular filtration barrier is lost in…
nephrotic syndrome, resulting in albuminuria, hypoproteinemia, generalized edema and hyperlipidemia.
Renal Clearance Equation
Cx = UxV/P
If Cx < GFR, then there is…
net tubular reabsorption of X.
If Cx > GFR, then there is…
net tubular secretion of X.
To calculate GFR, use…
inulin because it is freely filtered and is neither secreted or reabsorbed.
Normal GFR is about…
100 mL/min.
Creatine clearance is an approximate measure of…
GFR but it slightly overestimates GFR becasue creatine is moderately secreted by the renal tubules.
Effective renal plasma flow (ERFP) can be estimated using…
para-aminohippuric acid (PAH) clearance because it is both filtered and actively secreted in the proximal tubule. Nearly all PAH entering the kidney is excreted.
ERPF underestimates…
the true RPF by about 10%.
RBF =
RPF/(1-Hct)
FF =
GFR/RPF
Filtered load =
GFR x plasma concentration
In the kidneys, prostaglandins normally…
dilate the afferent arteriole leading to: -increased RPF -increased GFR (FF remains constant) **NSAIDs block this.
In the kidneys, angiotensin II acts to…
constrict the efferent arteriole leading to: -decreased RPF -increased GFR -increased FF **ACE inhibitors block this.
Excretion rate =
V x Ux
Reabsorption rate =
filtered - excreted
Secretion rate =
excreted - filtered
At a normal plasma level, glucose is…
completely reabsorbed in the proximal tubule by Na/glucose costransport.
Glucosuria begins at…
about plasma glucose of 200. And at 375, all transporters are fully saturated.
Normal pregnancy decreases the reabsorption of…
glucose and amino acids in the proximal tubule leading to glucosuria and aminoaciduria.
Amino acids are reabsorbed by…
sodium-dependent transporters in the proximal tubule.
Hartnup disease is…
a deficiency of neutral amino acid (tryptophan) transporters in the proximal renal tubular cells leading to aminoaciduria.
Hartnup disease results in..
pellagra like symptoms.
Treat Hartnup disease with…
high-protein diet and nicotinic acid.
Fanconi syndrome is…
a reabsorptive defect in PCT
Fanconi is associated with…
increased excretion of nearly all amino acids, glucose, HCO3-, and PO43-.
Fanconi may result in…
metabolic acidosis.
Causes of Fanconi include…
Wilson disease, ischemia and nephrotoxins/drugs.
Bartter syndrome is…
a resorptive defect in the thick ascending loop of Henle that affects the Na/K/2Cl cotransporter.
Bartter syndrome results in…
hypokalemia and metabolic alkalosis with hypercalciuria.
Gitelman syndrome is…
a resorptive defect of NaCl in the DCT. Less severe than Bartter.
Gitelman syndrome leads to…
hypokalemia and metabolic alkalosis but without hypercalciuria.
Liddle Syndrome is…
increased Na+ reabsorption in the distal and collecting tubules (increased ENaC).
Liddle syndrome results in…
HTN, hypokalemia, metabolic alkalosis and decreased aldosterone.
Treatment for Liddle syndrome is…
Amiloride.
Angiotensin II
-affects baroreceptor function -limits reflex bradycardia -helps maintain blood volume and pressure
ANP is released from…
atria in response to increased volume; may act as a “check” on the RAAS; relaxes vascular smooth muscle via cGMP causing increased GFR and decreased renin
ADH primarily regulates…
osmolarity; it responds tolow blood volume states
Aldosterone primarily regulates…
ECF Na content and volume; responds to low blood volume states.
Renin is released from the kidneys in response to…
-decreased BP (JG cells) -decreased Na+ delivery to the macula densa -increased sympathetic tone (Beta-1 receptors)
The juxtaglomerular apparatus consists of…
JG cells (smooth muscle of the afferent arteriole) and macula densa (NaCl sensor in the distal convoluted tubule).
JG cells secrete…
renin.
The juxtaglomerular apparatus defends….
GFR via RAAS.
Beta-blockers can decrease BP by…
inhibiting beta1 receptors of the JGA causing decreased renin release.
Erythropoietin is released by…
interstitial cells in the peritubular capillary bed in response to hypoxia.
The proximal tubule cells convert…
25-OH vitamin D to 1,25 (OH)2 vitamin D which is the active form. 1alpha-hydroxylase is the enzyme.
Things that shift K+ out of the cell causing hyperkalemia
Digitalis HyperOsmolarity Insulin deficiency Lysis of cells Acidosis Beta-adrenergic antagonis
Things that shift K+ into the cell
-hypoosmolality -insulin -alkalosis -beta-adrenergic agonist (Insulin INto cells)
Low Serum Na+
nausea malaise stupor coma
High Serum Na+
irritability stupor coma
Low Serum K+
U waves on ECG flattened T waves arrhythmias muscle weakness
High Serum K+
wide QRS peaked T waves arrhythmias muscle weakness
Low Serum Ca2+
tetany seizures QT prolongation
High Serum Ca2+
Stones (renal) Bones (pain) Graons (abdominal pain) Psychiatric overtones (anxiety, altered mental status)
Low Serum Mg2+
tetany torsades de pointes
High Serum Mg2+
decreased DTRs lethargy bradycardia hypotension cardiac arrest hypocalcemia
Low Serum Phosphate
bone loss osteomalacia
High serum phosphate
renal stones metastatic calcifications hypocalcemia
Henderson-Hasselbalch Equation
pH = 6.1 + log(HCO3-/.03PCO2)
The predicted respiratory compensation for a simple metabolic acidosis can be calculated using…
the Winters formula. PCO2 = 1.5[HCO3-] + 8 +/- 2 If the measured PCO2 differs significantly from the predicted PCO2, then a mixed acid base disorder is likely present.
Type I Renal Tubular Acidosis
-defect in ability of alpha intercalated cells to secrete H+ -new HCO3- is not generated leading to metabolic acidosis -associated with hypokalemia -incresaed risk for calcium phosphate kidney stones
Causes of Type I Renal Tubular Acidosis
-amphotericin B toxicity -analgesic nephropathy -multiple myeloma -congenital anomalies of the urinary tract
Type II Renal Tubular Acidosis
-defect in proximal tubule HCO3- reabsorption leading to metabolic acidosis -associated with hypokalemia -increased risk for rickets
Causes of Type 2 Renal Tubular Acidosis
-Fanconi syndrome (wilson dz) -chemicals toxic to proximal tubule (lead, aminoglycosides) -carbonic anhydrase inhibitors
Type 4 Renal Tubular Acidosis
-hypoaldosteronism; aldosterone resistance; or K+ sparing diuretics -hyperkalemia impairs ammoniagenesis in the PT -decreased buffering capcity and decreased H+ secretion
Presence of casts in the urine indicates that hematuria/pyuria is of…
renal origin (vs. bladder).
RBC casts
-glomerulonephritis, ischemia or malignant HTN