Proximal Tubular Dysfunctions and Disorders of Water Balance - Gosmanova Flashcards
Which segments of the PT secrete organic compounds?
S2 and S3
What are the types of transport mechanisms present in the PT?
Primary active
Secondary active
Passive
Pinoctyosis
What substances are reabsorbed via Na cotransport in the PT?
Sugars
Amino acids
Phosphate
Citrate
What substances are reabsorbed via Na antiport in the PT?
H
What does angiotensin II promote in the PT?
Na / H antiporter (luminal)
HCO3 / Na cotransport (basolateral)
What can cause a defect in glucose reabsorption?
Mutation of SGLT2 glucose transporter (Hereditary Renal Glucosuria)
What can cause a defect in amino acid reabsorption?
Mutation of brush border transporter for cystine, ornithine, lysine, and arginine
Cystinuria
What can cause a defect in phosphate reabsorption?
Mutation in PHEX gene (X-linked hypophosphatemia - most common)
Mutation in FGF-23 (Hypophosphatemic rickets)
Increased FGF-23 production (Oncogenic hypophosphatemic osteomalacia)
What is Fanconi syndrome?
Collection of symptoms (different underlying causes) Aminoaciduria Glucosuria Hypophosphatemia Hyperchloremic metabolic acidosis Hypokalemia Uricosuria
What is an inherited cause of Fanconi syndrome?
Cystinosis
What are acquired causes of Fanconi syndrome?
Drugs (Tenofovir) Heavy Metals Toxins Dysproteinemias (Multiple myeloma) Acute tubular necrosis
What is the normal osmotic threshold for ADH and thirst?
ADH 280-290
Thirst 290-295
What is osmolar clearance?
Amount of water needed to excrete solutes at the concentration of solutes in plasma
What is the most common electrolyte disorder?
Hyponatremia
What is hyperosmolar hyponatremia?
Dilutional hyponatremia due to presense of osmotically active substances (glucose, mannitol, glycine)
