Renal tubular defects, electrolyte disturbances Flashcards
Mnemonic for remembering renal tubular defects?
The kidneys put out FABulous Glittering LiquidS.
Fa = Fanconi (1st defect, PCT)
B = Barter’s (thick ascending loop of henle)
G = Gittelman’s (DCT)
L = Liddle’s (last - collecting tubule)
S = syndrome of apparent mineralocorticoid excess (collecting tubule).
What is Fanconi syndrome?
Generalized reabsorptive defect in PCT; associated with excretion of nearly all amino acids, glucose, bicarb and phosphate; may result in metabolic acidosis
What are the causes of Fanconi syndrome?
Hereditary: Wilson’s, Tyrosinemia, Glyc storage dzs
Ischemia, multiple myeloma deposition, nephrotoxic drugs, lead poisoning
What is Barterr’s syndrome? What effects does it have on K+, Ca2+, and pH and why?
Autosomal recessive defect in NKCC2 transporter of thick ascending loop of Henle; reabsorptive defect. Results in hypokalemia (K+ not absorbed), hypercalciuria (Ca2+ not moving paracellularly as much (less K+ cycling)), and metabolic alkalosis (excessive Na+ delivered distally, increased aldosterone, which will increase H+ excretion and bicarb resabsorption).
What is Gitelman’s syndrome?
Autosomal Reabsorptive defect of NaCl in DCT. Less severe than Barterr’s syndrome?
What is the effect of Gitelman’s syndrome on K+, Mg2+, pH, and Ca2+?
Like Barter's, leads to hypokalemia and metabolic alkalosis. Also HYPOmagnesemia (less Mg absorption), and hypocalciuria/hypercalcemia.
What diuretic is similar to Barter’s?
Loop diuretics
What diuretic is similar to Gitelman’s?
Thiazide diuretics.
Why do thiazide diuretics and Gitelman’s lead to hypocalciuria?
Na transport into the cell from luminal side is reduced, causing decreased intracellular Na. Therefore, Ca/Na+ transporter on basolateral side will favor bringing more Na+ into the cell and Ca+ across basolateral membrane.
What is Liddle’s syndrome? What are the effects on BP, K+, pH?
Autosomal Dominant Gain of function mutation, increasing activity of ENac channel in collecting ducts.
BP: Increases
K+: Decreases (increase sodium in, means Na/K+ brings more K+ into cell, more K+ gets excreted).
pH: metabolic alkalosis (less intracellular K+, H+/K+ATPase on alpha intercalated cells will pull in more K+ and push out more H+).
What is syndrome of apparent mineralocorticoid excess?
Hereditary deficiency in 11beta-hydroxysteroid dehydrogenase, which normally converts cortisol to cortisone in cells w/ mineralocorticoid receptors BEFORE cortisol finds the receptors
Increases mineralocorticoid activity: HTN, hypokalemia, metabolic alkalosis…. with low serum aldo.
What can syndrome of apparent mineralocorticoid excess be acquired from?
Glycyrhhetic acid in licorice, which blocks activity of 11beta-hydroxysteroid.
What do all renal tubular acidoses lead to?
Normal anion gap (hyperchloremic metabolic acidosis).
What is RTA type 1? What Urine pH?
Distal, defect in ability of alpha intercalated cells to secrete H+. Urine pH > 5.5
- No new bicarb, acidosis.
- Associated with hypokalemia.
- Increased risk for calcium phosphate stones due to increased urine pH and increased bone turnover (?)
What are causes of RTA type 1?
amphotericin B toxicity, analgesic nephropathy, congenital anomalies/obstruction
