Diuretics

Question 1

Name the three sodium basolateral channels and which diuretics act on them

Answer 1

In TAL is NKCC and loop diuretics
In DCT NCC thiazides and ENaC k sparing and aldosterone
In CD ENaC k sparing and aldosterone

Question 2

Which diuretic doesn’t act on an Na channel

Answer 2

Spironolactone acts on ROMK

Question 3

Prescribe a loop diuretic for an indication

Answer 3

Furosemide for chronic HF or pulmonary oedema due to LV failure

Question 4

Which diuretic is the most potent

Answer 4

Loop diuretics. Risk of hypovolemia

Question 5

Prescribe a thiazide for an appropriate indication

Answer 5

Chlortalidone for hypertension

Bendroflumethiazide for mild or mod chronic heart failure odema

Question 6

Prescribe a k sparing diuretic for an appropriate indication

Answer 6

Weak diuretics eg amiloride hydrochloride

Given with a thiazide or Loop as an alternative to potassium supplements for HTN

Question 7

Prescribe an aldosterone antagonist for an appropriate indication

Answer 7

Spironolactone for oedema and ascites caused by liver cirrhosis
Or in conns syndrome (hyperaldosteronism)
Or mod to severe heart failure

These are also K sparing

Question 8

Name buffers so that urine isn’t too acidic

Answer 8

NH4 and H2PO4

Question 9

What do you lose in vomit and diarrhoea and what results

Answer 9

Lose h in vomit so alkalosis

Lose K and HCO3 in diarrhoea so acidosis

Question 10

What electrolyte loss do you get with furosemide

Answer 10

Na
Cl
K

Question 11

How does aldosterone change K levels

Answer 11

Decreases them due to action on ENaC, risk of hypokalemia

Question 12

Causes of hypokalemia

Answer 12

Diarrhoea 
Metabolic alkalosis
Magnesium deficiency
Hyperaldosteronism (conns) 
Thiazide and loop diuretics

Question 13

Symptoms of hypocalcemia

Answer 13

Weakness, tetany, lip/finger tip parasthesia, irritable, hallucinations (tripping on TRPV5), paranoia, negative inotrope

Question 14

Describe homeostasis of calcium

Answer 14

Low calcium PTH increases and calcitonin from thyroid decreases
PTH acts on kidneys to produce calcitriol, which then acts on GI to increase GI absorption, bone to increase osteoblasts and kidneys to reduce excretion. Less calcitonin means less kidney excretion

Question 15

How is calcium reabsorbed in a nephron

Answer 15

In Pct and TAL its paracellular passive
In DCT it’s TRPV5 basolateral membrane, binds to calbindin, transported out with 3Na2
Ca

Question 16

Causes of hypocalcemia

Answer 16

Loop diuretics
PTH deficiency 
Vitamin d deficiency 
Malabsorption 
Hyperphosphataemia

Question 17

What is magnesium important for

Answer 17

Neuronal signalling, cardiac excitability, dna synthesis, intracellular signalling

Question 18

Where is magnesium mostly absorbed

Answer 18

TAL!

Question 19

Symptoms of hypomagnesemia

Answer 19

Muscle spasms, hyperreflexia, tetany, seizures, dysrhythmias, hypokalemia, hypocalcemia

Question 20

Causes of hypomagnesemia

Answer 20

Malabsorption 
Chronic diarrhoea 
Malnutrition
Diuretics 
Polyuria 
Metabolic acidosis 
Alcoholism, chronic pancreatitis

Question 21

Symptoms of hypokalemia

Answer 21

Weakness, constipation, polyuria, cells more excitable so arrthymias

Question 22

How do some diuretics cause hypokalemia and others cause hyperkalemia

Answer 22

K sparing eg amiloride cause hyperkalemia cause blocking ENaC means Na k pump works less so k stays on the outside. This makes sense

Thiazide and loop cause hypokalemia because their Na blocking occurs earlier in the nephron. This means it actually increases Na transport later in the tubule in the principle cells, so increases Na k pump and more k gets secreted
Also, thiazide and loop blocking early Na water reabsorption leads to a faster flow rate so secreted k is washed away faster

Question 23

What would you treat cerebral oedema with

Answer 23

Mannitol (an osmotic diuretic)

Question 24

Name risks associated with different diuretics

Answer 24

Loop- hypovolemia and uraemia
Thiazide- hypokalemia and uraemia
K sparing- hyperkalemia and gynaecomastia (spiro)

Question 25

What effects do alcohol and coffee have on the kidney

Answer 25

Alcohol inhibits ADH

Coffee increases GFR and decrease Na reabsorption

Question 26

What is diabetes insipidus

Answer 26

Central DI is no ADH released

Nephrogenic DI is no response to ADH in collecting duct (acts on AQP2 only)