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Name two mechanisms which bring K+ into the cell
- Insulin
- Beta adrenergic stimulation
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Name two mechanisms that moves K+ out of the cell
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What hormone regulates potassium
Aldosterone
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What is the normal range of potassium level?
3.5-5.5
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What are symptoms of K+ overload?
- Generalized fatigue,
- Weakness
- Paresthesias
- Paralysis
- Palpitations
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What will an electrocardiogram reading show in the case of high potassium
- Tall, tented T waves (mild)
- Depressed ST, prolonged PR, wide QRS (severe)
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What are causes of high potassium levels
- renal failure
- potassium sparing diuretics
- urinary obstruction
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What are the causes of low potassium levels
- Renal tubular acidosis
- Hyperaldosteronism
- Magnesium depletion
- Vomiting or nasogastric suctioning
- Inadequate diet
- Medications - diuretics, beta-adrenergic agonisits, theophylline
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What are some physical signs of low potassium
- Hypotension
- Abdominal cramping
- Hypoventilation or respiratory distress
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What are the cardiac responses to low potassium
- Bradycardia
- Ventricular arrythmia
- Cardiac arrest
- Premature atrial or ventricular beats
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What is the normal range for Calcium
8.8-12
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What causes high calcium levels?
- Hyperparathyoridism - causes increased GI absorption without recnal excretion
- Metastatic bone cancer - increased osteoclastic activity
- Ingestion/infusion of calcium
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What are the symptoms of high calcium?
- Nausea/vomiting
- Alterations in mental status
- Adominal or flank pain (think of GI manifestations and bone mets)
- Constipation
- Lethargy
- Weakness and joint aches
- Polyuria
- Headache
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What are causes of low calcium?
- Hypoparathyroidism/parathyroidectomy
- Malabsorption of Calcium or vitamin D from gut - Crohn's, sprue, pancreatitis, gastric resection or bypass or gastrojejunostomy
- Lack of sun exposure
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What are symptoms of low calcium?
- Numbness
- tingling
- muscle cramping
- irritability
- seizures
- respiratory disurbances
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What is the normal level of phosphorus?
2.0-4.5
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What are causes of low phorphorus?
- Vitamin D Deficiency
- Manesium/aluminum products (Antancids)
- Alcohol abuse (long term)
- Reneal excretion
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What are symptoms of low phosphorus levels?
- Weakness of skelatal or smooth muscle
- Rhabdomyolysis via ATP depletion (alcohol withdrawal)
- Respiratory insufficiency
- Confusion, seizures, and coma
- Peripheral neuropathy
- Hemolytic anemia
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Where is magnesium absorbed and excreted
- Absorbed in ileium
- excreted by stool and urine
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What organ regulates magnesium levels?
Kidneys - stores in bone may be mobilized as needed.
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What are causes of high magnesium?
- Errors in administration
- Lithium intoxication
- Inadequate excretion from kidney or gut
- Release of cellular manesium by tumor lysis syndrome, rhabdomylosis
- Hypothyroidism/hypoparathyroidism
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What are symptoms of high magnesium
- 2-4 - nausea and vomiting, sking flushing, weakness, lightheadedness
- 3.5-5 - Disapperance of deep tendon reflex, Muscle weakness
- 5-6 - Hypotension, vasodilation
- 8-10 Arrythmia, atrial fibrillation
- >10 asystole, heart block, coma, death
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What are the causes of low magnesium levels?
- GI loss - malabsorption, radiation injury to bowel, diarrhea, laxative abuse, neoplasm
- Malnutrition
- Renal issues
- Endocrine - primary aldosteronism
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What are symptoms of low magnesium levels
- Hyperactive deep tendon reflexes
- Muscle cramps
- Muscle fibrillation
- Troousseu and Chvostic sings
- Dysarthria and dysphagia
- CNS excitability - irritability and combativeness, disorientation, pyschosis, ataxia
- Cardiac dysrhytmias
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Why is it important to to measure both bound and ionized calcium levels?
- Of the calcium in plasma, 50% is bound to plasma protiens, and about 40% is in the free or ionized form.
- Ionzied calcium has the most important physiciolgic findings.
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What functions does calcium play in the body
- Major cation for structure of bones and teeth
- Enzymatic cofactor for blood clotting
- Required for hormone secretion
- Needed for function of cell receptors
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Where is intracellular calcium located?
In the mitochondria
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What is the function of phosphate in the body
- Functions acts as intracellular and extracellular anion buffer in the regulation of acid-base balance.
- In the form of ATP, it provides energy for muscle contraction.
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