Flashcards in Proximal and Distal Tubule Disorders Deck (31):
How many sections are in the PT ?
Two, the first 2/3 is the PCT and the final 1/3 is the PST (parsa recta)
How many segments are in the PCT ?
Three, S1 S2 and S3
What are the functions of the PT ?
Reabsorption of Water and electrolytes
Secretion of organic compounds
Hormonal function in vitamin D synthesis
How is insulin taken in by the PT ?
Is H secreted in the PT ?
Yes, H+ is secreted by the Na-H exchanger
Is the PT succeptable to ischemia ?
Yes because it has a high level of mitochondria activity it is very dependent on ATP for proper function
What are the six basic defects in the PT ?
1. Defective Solute Influx
2. Leakage back into interstitum
3 Decreased Solute flux into blood
4. Defective energy generation
5. Increased back-flux across tight junctions.
6. Defective transport recycling
What is a generalized PT dysfunction ?
It is usually due to a defect in energy generation ( NaKATPase ) or dysfunctional cellular organelles affecting transport protein recycling
What is an isolated PT dysfunction ?
Usually a defect in a specific transport protein
What is renal glucosuria ?
An AR inherited trate affecting the SGLT-2 glucose transporter
What is Cystinuria ?
An AT inherited trare caused by a mutation in brush border transporter responsible for reabsorption of cystine and AA ornithine, lysine, and arginine
What will cystineuria cause ?
Cystine stones and cystine crystals in the urine
What are the inherited defects in phosphate reabsorption ?
X-Linked hypophosphatemia (PHEX)
A- Dom Hypophosphatemic Rickets (FGF23)
A-Rec Hypophosphatemic rickets
What is the acquired defect in phosphate transport ?
Oncogenic Hypophosphatemic Osteomalacia (FGF23)
What is the most common phosphate wasting disorder ?
X Linked Hypophosphatemia
What causes X-Linked Phosphatemia ?
A defect in PHEX --> Increased circulating factor FGF-23 that down regulates activity of phosphate transporter rather than transport protein itself
What does X-L-P cause
Ricketts in children and osteomalicia in adults
What causes Falconi Syndrome ?
Can be inherited but usually is acquired.
DEFECTIVE BINDING of Na with transport proteins, defective insertion of carriers into brush border membranes. Impaired mitochondrial energy generation and leaky tight junctions.
Bartter, Gitelman, and Liddle syndromes are disorders of what ?
Nephrogenic diabetes insipidus is a disorder of what ?
Distal renal tubular acidosis is a disease of what ?
Ammoniagenesis and urinary acidification.
What are the defects in neonatal Bartter Syndrome ?
Autosomal Recessive: Na-K-2Cl cotransporter and the luminal potassium channel (ROMK) in the thick ascending limb of the loop of hen lie.
What is the problem in classical Barter syndrome ?
Autosomal Recessive : Mutations in the luminal chloride channel in the distal tubule
Does the difference between the Bartter Syndromes depend on the transporter involved ?
No it is determined by the clinical symptoms
What causes Gittlemans syndrome ?
It is an Autosomal Recessive disorder associated with mutation s in the thiazide- sensitive cotransporter o the luminal side of the distal convoluted tubule
What are the symptoms of neonatal Bartter Syndrome ?
Polyhydramos, preterm delivery, fever and dehydration in infancy, failure to thrive, Hypercalcinuria, Hypercalcinosis.
What are the symptoms of Classical Bartter Syndrome ?
Presents later in infancyand is characterized by a failure to thrive, Polydipsia, Dehydration and salt craving
Since the presentations of both types of Bartter Syndrome sound alike how the hell do you tell them apart?
Classical patients do have Hypercalciuria but do NOT HAVE NEPHROCALCINOSIS
What is Nephrogenic Diabetes Insipidus ?
It is characterized by an inability to concentrate the urine despite normal or elevated levels of the antidiuretic hormone Arginine Vasopressin. The final effect is a failure of the insertion of the Aquaporin 2 channel in the lumen of the CD of the nephron
What are the causes of acidosis with an elevated anion gap ?
Inborn errors of metabolism such as organic acidemias, Ketoacidosis, lactic acidosis secondary to hypo perfusion.