Distal Renal Tubular Diseases Flashcards
(42 cards)
What mutations cause Bartter syndrome?
- Bumetanide-sensitive Na+-K+-Cl-cotransporter (NKCC2)
- ATP-sensitive K+ channel (ROMK)
- Cl- channel A subunit (CLCNKA)
- Cl- channel B subunit (CLCNKB)
- Barttin (necessary for insertion of Cl- channel A and B subunits in cell membrane in kidney and inner ear)
Classic Bartter Syndrome is characterized by?
- failure to thrive
- polydipsia
- episodes of dehydration
- episodes of salt craving
- Affected patients have hypercalciuria
Difference between Neonatal and classic Bartter Syndrome?
Classic:
- It presents later in infancy
- do not usually have nephrocalcinosis as do patients with neonatal Bartter syndrome.
Mode of inheritance of Bartter Syndrome?
Autosomal recessive
What features distinguish between Bartter and Gitelman?
- hypomagnesemia
- elevated urine magnesium
- low urine calcium excretion
Mutations associated with Gitelman Syndrome?
mutations in the thiazide-sensitive Na+/Cl- cotransporter (TSC)
(on the luminal side of the distal convoluted tubule)
Bartter syndrome and Gitelman syndrome are both syndromes of what?
hypochloremic metabolic alkalosis
Bartter syndrome and Gitelman syndrome are associated with hyperplasia of…?
the juxtaglomerular apparatus
What else can cause Hypochoremic metabolic alkalosis?
- chronic vomiting
- diuretic abuse
- congenital chloride diarrhea
- cystic fibrosis
- ingestion of formula deficient in chloride
Why are patients with neonatal and classic Bartter syndromes usually more severely affected than patients with Gitelman syndrome?
Mmore severe Na+ wasting in Bartter syndrome than Gitelman’s
- because Bartter’s syndrome is due to problems in the Thick AL of LOH, where more Na+ should normally take place
What causes Liddle syndrome?
- results from a gain-of-function mutation in the β or γ subunit of the epithelial sodium channel (ENaC).
Mode of inheritance of Liddel Syndrome?
Autosomal dominant
Tx of Liddle syndrome?
- low sodium diet
2. potassium-sparing diuretics.
Liddle syndrome is characterized by?
- increased absoprtion of sodium
- hypertension
- hypokalemic metabolic alkalosis
Disease characterized by an inability to concentrate the urine despite normal or elevated levels of the antidiuretic hormone arginine vasopressin (AVP
Nephrogenic diabetes insipidus (NDI)
What causes Nephrogenic diabetes insipidus (NDI)?
failure of the vasopressin-sensitive water channels (aquaporin 2, AQP2) to insert into the luminal membrane of the collecting duc
- due to:
1. defective V2 receptor (90% cases)
2. Defective AQP2 (10% cases)
Symptoms of Nephrogenic diabetes insipidus?
- polydipsia
- polyuria
- irritability
- constipation
- formula intolerance with vomiting
- failure to thrive
- hyperthermia
- Severe dehydration can lead to hypoperfusion of the brain, kidneys, and other organ systems and lead to mental retardation and renal damage. The huge volumes of urine produced can lead to hydronephrosis, megaureter, and bladder dysfunction
What is Renal Tubular Acidosis (RTA)?
Hyperchloremic metabolic acidosis with a normal plasma anion gap.
What does a higher than normal anion gap tell you?
Indicates the presence of an unexpected, unmeasured serum anion
Examples of unmeasured serum anions that cause an increase in the anion gap?
MUDPILES
- Methanol
- Uremia
- Diabetic Ketoacidosis
- phenformin and Paraldehyde
- Isoniazide, Infection, Iron
- Lactic Acidosis
- Ethylene glycol, ethanol
- Salicylates
Causes of acidosis with a normal anion gap (hyperchloremic acidosis)
- Renal Tubular acidosis
- Exogenous Chloride
- GI bicarbonate loss (Diarrhea)
Type II Renal Tubular Acidosis
- where is the defect?
- what is the result of this defect?
- Proximal Tubule defect
- leads to a decreased threshold for bicarbonate reabsorption
- Patients with type II RTA are able to achieve a urine pH less than 5.5 in the face of a low serum bicarbonate. (mostly variable)
What RTA is associated with Fanconi Syndrome?
Type II RTA
Type I Renal Tubular Acidosis (RTA)
Characterized by:
- impaired ammonium excretion and impaired acid secretion by alpha-intercaleted cells
- inability of the collecting duct to decrease the urinary pH BELOW 5.5 even with systemic acidosis (pH > 5.5!)