Potassium Flashcards
Hyper- and HypoK. Study in order (follows a diagnostic algorithm)
Low Potassium:
What are the 3 first investigations and what results prompt what?
- Urinary K
- Transtubular K Gradient
- Urinary K/ Urinary creatinine
If one is low: Gastrointestinal loss (Diarrhea/laxatives). RARE Familial Hypokalemic Periodic Paralysis
If one is high: Check BP
Low Potassium:
K is not being lost in the GI tract. You measured BP. What would normal or low BP mean/prompt?
- Metabolic Acidosis: RTA (1 or 2) or DKA
- Metabolic Alkalosis: Check urinary Cl-
Low Potassium:
Low K due to metabolic Alkalosis. You measured urinary Cl-. What do the results mean?
- Low U Cl-: Vomiting
- High U Cl-: Diuretics, Low Mg, Barterr or Gitelman Syndrome.
Low Potassium:
K is not being lost in the GI tract. You measured BP. What would high BP prompt?
Check aldosterone AND plasma renin:aldosterone
Low Potassium:
High BP. You checked for Aldo and Renin:Aldo. What does high Aldo and high Renin:Aldo mean?
- Renal artery stenosis
- Renin-Secreting tumor
(If you have more renin than aldosterone, and your aldosterone is still normal/high, the problem is with renin)
Low Potassium:
High BP. You checked for Aldo and Renin:Aldo. What does high Aldo and low Renin:Aldo mean?
Conn Syndrome:
* Aldosterone secreting adenoma
* Bilateral adrenal hyperplasia
* Adrenal carcinoma
Low Potassium:
High BP. You checked for Aldo and Renin:Aldo. What does low Aldo and low Renin:Aldo mean?
- CAH
- Cushing’s
- Liddle syndrome
- Apparent mineralocorticoid excess
High Potassium:
What’s the first (clinical) test that follows hyperkalemia (Serum K >5 meq/L) and what should be done afterwards regardless of the result?
ECG. If consistent with hyperK or not, you have to exclude lab error:
1. Haemolysis
2. Excessive tourniquet time
3. Severe leukocytosis or trombosis
High Potassium:
After checking ECG and potential lab errors, what 7 things should you check for next and what would they indicate?
If the patient has:
1. Tissue injury (rhabdo, tumor lysis syndrome, haemolysis, GI bleed)
2. Insulin deficiency
3. Metabolic acidosis
4. Hyperosm
5. Drugs (digoxin tox, succinylcholine, octreotide, B-blockers, somatostatin)
6. Oleander tox (very toxic plant)
7. Hyperkalemic periodic paralysis (VERY RARE)
If yes, the hyperK is due to redistribution
High Potassium:
If hyperK is not due to redistribution, what 5 things could explain it?
- Severe decrease in Effective Arterial Blood Volume (EABV)
- Decreased flow and Na delivery in Cortical Collecting Duct (CCD)
- Ureterojejunostomy (surgery that redirects the flow of piss, e.g. done if bladder is removed)
- Kidney failure (Check eGFR<20!!!)
- RTA Type 4
High Potassium:
If its Type 4 RTA, what 2 things do you want to check?
If it’s due to hypoaldosteronism or collecting tube defects
High Potassium:
If the T4 RTA is caused by collecting duct defects, what 5 things could be causing these defects?
-Meds
* Amiloride
* Triamterene
* Spironolactone
* Eplerenone
* Trimethoprim
* Pentamidine
-Tubulointerstitial disease
-Urinary tract obstruction
-Defective mineralocorticoid receptor
-Gordon syndrome
High Potassium:
If the T4 RTA is caused by Hypoaldosteronism, what should you check next?
Renin
High Potassium:
T4 RTA due to Hypoaldosteronism. You measured renine. What would high renin mean?
-Adrenal insufficiency (Addison’s)
-Congenital enzyme defects
-Meds
* ACE inhibitors
* Angiotensin Receptor Blockers (ARBs)
* Heparin
High Potassium:
T4 RTA due to Hypoaldosteronism. You measured renine. What would low renin mean?
-Meds
* NSAIDs
* COX-2 inh
* Calcineurin inh
-DM
-HIV infection
