Distal Renal Tubular Disorders - Ault Flashcards
What percentage of Na is absorbed in the distal tubule?
7%
What transporter in the distal tubule is responsible for the Na reabsorption?
The Na-Cl co-transporter known as the thiazide-sensitive cotransporter (TSC)
How is neonatal bartter syndrome passed on?
autosomal recessive
Explain neonatal bartter syndrome?
polyhydraminos, preterm delivery and episodes of fever and dehydration in infancy. Failgure to thrive, hypercalciuria and nephrocalicnosis.
What are the two defective transporters in people with neonatal bartter syndrome?
NaK2Cl co-transporter
Luminal Potassium Transporter ROMK in the TALH
How is classic bartter syndrome passed on?
Autosomal recessive (like neonatal bartter syndrome)
Explain classic bartter syndrome?
Presents later in infancy, failure to thrive, polydipsia, episodes of dehydration and salt craving. Hyper calciuria but not usually nephrocalcinosis.
What is the mutation in classic bartter syndrome?
Luminal chloride channel in distal tubule (ClC-Kb)
How is gitelman’s syndrome passed on?
autosomal recessive
What do gitelman’s affected individuals present with?
Less failure to thrive that bartters
Dehydration or tetany
What features of gitelman’s distinguish it from the types of bartters syndrome?
hypomagnesemia, elevated urine magnesium, low urine calcium excretion.
What mutation is associated with gitelman syndrome?
mutation in the thiazide-sensitive cotransporter (TSC)
Both Bartters and Gitelmans Syndrome (hypochloremic metabolic alkalosis) have been associated with hyperplasia of the juxtaglomerular apparatus. Why
idk
How can you distinguish bartter and gitelman syndromes from other chronic hypochloremic metabolic alkalosis (ie chronic vomiting diuretic abuse congential chloride diarrhea, cystic fibrosis, ingestion of formula deficient in chloride?
idk again
Why are patients wth neonatal and classic bartter syndromes usually more serverly affected than patients with gitelman’s syndrome?
hopefully the last time idk
What is liddle syndrome
A gain of fxn mutation in the beta or gamma subunit of the epithelial sodium channel (enac). results in hyperabsorption of sodium with htn and hypokalemic metabolic alkalosis. it is treated with low na diet and potassium-sparing diuretics
If a parent had liddle syndrome, bartters or gitelmans syndrome, which must you be most concerned about passing on to your children?
liddles, because it is autosomal dominant
What is the g-protein coupled receptor that triggers the reabsorption of water from the collecting duct?
AVP/Vasopressin/ADH
What characterizes nephrogenic diabetes insipidus?
an inability to concentrate the urine despite normal or elevated levels of ADH.
What is the final pathway malfunction in nephrogenic diabetes insipidus?
filure of the vaspressin-sensitive water channels (AQP2) to insert into the luminal membrane of the CD.
What are the two dysfunctions that can cause a lack of ADH responsitivity?
a mutation in the AVPR2 receptor
a mutation in the aquaporin itself
Of the two ways to disrupt the AQP2, what is the more common reason that leads to nephrogenic diabetes insipidus?
deletion or point mutation of the X chromosome XQ28, in 90% of cases.
What are the symptoms of nephrogenic diabetes insipidus?
polydipsia, polyuria, irritability, constipation, formula intolerance from vomiting, failure to thrive, hyperhtermia.
How does DDAVP work?
When DDAVP binds to AVPR2, it causes a release of Factor 8, to induce clotting factors.
