Dyskalemias Flashcards
Where is concentration of K regulated?
Cells and kidneys
How do cells regulate K?
Via buffering/short term
How do kidneys regulate K?
Long term
What factors that affect K movement into and out of the cells?
- pH
- Insulin
- Plasma K level
- Catecholamines
- Cell production
- Cell destruction
What controls cellular K movement?
The activity activity of Na/K ATPase (affected by Beta-2 receptors, insulin, pH)
-We take advantage of this knowledge in therapies
What renal regulation of K is present?
- Plasma K
- Aldosterone
- Non-resorbable anions
- Flow to the distal nephron
What is a normal range of K?
3.6-5.1
Is hypokalemia preventable and easy to treat?
Yes and yes
What are signs and symptoms of hypokalemia?
Muscle weakness, cardiac dysrhymthmia, rhabdomyolysis, chronic kidney disease (long-term effect)
What are some causes of hypokalemia?
- Poor intake (rare)
- Renal conservation of K (15mEq)
- Anorexia, alcoholic, elderly, poor
Which is more common to cause hypokalemia, decreased intake or increased loss?
INCREASED LOSS
What are the 3 main routes of K loss?
- Cellular shift
- GI losses
- Renal loss
What are some renal losses of K?
- Diuretics
- Vomiting or NG suction
- Diabetic ketoacidosis
- Primary hyperaldosteronism
- Renal tubular acidosis
- Renovascular HTN
- Excessive IV fluids
- Cushing’s Syndrome
- Pseudohyperaldosteronism
- Congenital adrenal hyperplasia
- Bartter’s and Gitelman’s
- Toulene
- PCN
What type of diuretics cause hypokalemia?
Loop and thiazide
Is K loss due to loop and thiazide diuretics dose related?
YES
How do loop and thiazide diuretics cause K loss
- Increase distal flow
2. Enhanced secretion of aldosterone (underlying disease state and intravascular volume depletion)
What can be given with loop and thiazide diuretics to prevent hypokalemia?
K sparing diuretics
What 3 conditions is primary hyperaldosteronism seen in?
- Adenoma: 65%
- Hyperplasia: 30%
- Carcinoma: 5%
What 3 features are seen in primary hyperaldosteronism?
- Hypokalemia
- Metabolic alkalosis
- Mild hypernatremia
What is the treatment for primary hyperaldosteronism?
Surgery, spironolactone, eplerenone
What are the 2 non-renal causes of hypokalemia?
Cellular shift and GI losses
What are the 4 topics discussed relating to hypokalemia caused by cellular shift?
- Insulin
- Alkalemia
- Catecholamines
- Pseudohyperkalemia
What is the effect of insulin on K?
Insulin causes K to be driven into cells by the Na/K ATPase (insulin and D50 can actually be used as a temporary treatment for hyperkalemia)
What is K in diabetic ketoacidosis?
K is normal to high in serum (no insulin, K not going into cells) –> Total body depletion of K
-Can lower K levels with insulin therapy
How does metabolic or respiratory alkalosis cause hypokalemia?
To maintain electorneurtality, there is an exchange of H for K (K is going into cells)
-Again, can give bicarb (inducing a “alkalosis” to treat hyperkalemia by driving K into cells
How do catecholamines cause hypokalemia?
B2 receptor activity causes the Na/K ATPase to drive K into cells
When can you see hypokalemia due to catecholamines?
Times of physiological stress:
- Coronary ischemia
- Delirium tremens
- Acute head trauma
- After CPR
* Catecholamine induced hypokalemia can be used as a temporizing measure for hyperkalemia
What patients can you see a pseudohyperkalemia in?
Acute myeloid leukemia
What is seen in pseduohyperkalemia induced by acute myeloid leukemia?
- Profound leukocytosis
- High metabolic activity
- Avoided by cooling or quick separation (Patient should be asymptomatic)
Are GI sources a significant cause of K loss?
Ehhh.. all GI secretions contain some K, renal losses are more significant
What are some sources of GI loss of K?
- Diarrhea
- Surgical drains
- Vipoma
- Villous adenoma
- Fistulas
How can diarrhea lead to profound hypokalemia?
A prolonged course… leads to renal conservation (less than 15mEq/day)
What is a rare, potentially fatal complication of hyponatremia?
Periodic paralysis
Why is periodic paralysis seen in hypokalemia potentially fatal?
When respiratory muscles are involved
What levels are seen hypokalemic periodic paralysis?
Super low 1.5 to 2.5
Can there be hyperkalemic forms of periodic paralysis?
YES… never assume either way because they have similar symptoms?
What is the familial association with periodic paralysis from hypokalemia?
Autosomal Dominant
What is an association of periodic paralysis and what population is this seen in?
Thyrotoxicosis… Chinese males
Treating what conditions can cause hypokalemia and why?
Anemia and leukopenia –> K is uptook by new, developing cells
When do you see hypokalemia post-treatment of anemia and leukopenia?
48 hours after treatment
What can be given for anemia?
Folic acid or B12 supplements
What is given for neutropenia?
GM-CSF
Do you see hypokaemia in Fe deficient anemia?
NO… it is a slower process
What is hyperkalemia?
K above 5.1
What can cause hyperkalemia?
- Increased intake
- Shift out of cells
- Poor renal function: Acute or chronic
If there is normal kidney function, is it common to OD on oral K?
NO… it is very uncommon