W10 Electrolyte imbalance (MAH) Flashcards
Electrolytes
What are the significant electolytes?
What do they do?
- Electrolytes are substances that, when dissolved in a solution, create electrically charged particles called ions
- Electrolytes are essential for basic life functioning, such as maintaining electrical neutrality in cells and generating and conducting action potentials in the nerves and muscles
- Significant electrolytes include sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonates. Electrolytes come from our food and fluids
- Electrolytes help move nutrients into body’s cells and help move waste out of the body’s cells
- Electrolytes maintain a healthy water balance, and help stabilise the body’s acid/base (pH) level.
What are the key electrolytes?
what are their roles?
- K+ play a vital role in muscle contraction and nerve cell function
- Na+ are primarily responsible for maintaining fluid balance and transmitting nerve impulses
- Cl- help balance fluid levels
- Mg2+ are involved in various enzymatic reactions and play a role in muscle and nerve function too
- Ca2+ are essential for muscle contraction, blood clotting, and maintaining bone health
- PO43- contribute to energy metabolism and DNA synthesis
Maintaining the balance of electrolytes in our body is crucial for overall health:
- proper diet and hydration
- Imbalance:
» dehydration
» muscle cramps
» irregular heartbeat
» seizures
Diagnostic tests: Electrolytes and Anion Gap
What are the Typical reference ranges for commonly requested tests?
- Serum Sodium 133 – 146 mmol/L
- Serum Potassium 3.5 – 5.3 mmol/L
- Serum Urea 2.5 – 7.8 mmol/L
- Serum Chloride 95 – 108 mmol/L
- Serum Bicarbonate 22 – 29 mmol/L
- Serum Phosphate 0.8 – 1.5 mmol/L
- Serum Magnesium 0.7 – 1.0 mmol/L
- Serum Albumin 35 – 50 g/L
- Serum Total Protein 60 – 80 g/L
- Serum Osmolality 275 – 295 mmol/kg
NB: ranges may differ between laboratories.
* Population samples
* Average +/- 2 s.d
* 95% confidence
* 5% of normal can reside outside of this
Sodium homeostasis:
What are the normal ranges?
What are the functions
- 135 to 145 mmol/L
- Main extracellular ion – [Na] is higher OUTSIDE of the cell
- Maintains fluid balance – NA attracts water
- Plays a major role in the action potential of nerves and muscle cells – ↑ [Na] equals ↑
neuromuscular excitability
Regulation:
* RAAS causes NA retention – ↑ [Na]
* Natriuretic hormones causes [Na] excretion – ↓
[Na]
Sodium Normal range: 135 to 145 mmol/L
Tests?
Test:
* routine lab test for non-specific health complaints
* Monitoring at risk patients:
* i.v. fluids
* Risk of developing dehydration
* Hypertension
* heart failure
* Liver disease
* Kidney disease
* Osmolality of blood / urine
* If altered then investigate [urine sodium]
Interesting facts about sodium: (for info)
Can ↑ plasma Na:
* Recent trauma, surgery, or shock because
blood flow to the kidneys is decreased.
* Lithium and anabolic steroids
* Corticosteroids, laxatives, cough
medicines and oral contraceptives
Can ↓ plasma Na:
* Drugs such as diuretics, sulphonylureas,
ACE inhibitors, heparin, ibuprofen
(NSAIDs), carbamazepine, tricyclic
antidepressants, and vasopressin
What are the causes of hyponatremia? (low plasma [Na])
What are the signs and symptoms?
Caused by either losing more sodium than water, or gaining more water than sodium
* Low dietary sodium intake
* Primary polydipsia
* Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
* Diuretics
* Vomiting
* Diarrhoea
* Congestive heart failure
* Renal disease
* Liver disease
S/S
* Neuro: seizures and coma
* Headaches, tired, weakness, nausea, vomiting
* Respiratory arrest
What are the causes of hypernatremia? (high plasma [Na])
What are the signs and symptoms?
CAUSE:
* Unreplaced fluid loss via the skin
(extensive burns, fever, exercise, and exposure to high temperatures)
* Unreplaced fluid loss via gastrointestinal tract (excessive vomiting, or diarrhoea)
* Osmotic diuresis
* Hypertonic saline administration
* Hypertonic tube feeding
* Diabetes
* OTC meds with lots of salt
* Inhalation of salt water
S/S
* Dehydration
* Tachycardia
* Agitation and restlessness
* Disorientation
* Weakness
* Irritability
* Stupor > unconscious
* Coma
Potassium:
Functions?
Regulation?
- Major ICF cation (98% is intracellular)
- Potassium plays a key role in maintaining cell
function - Almost all cells possess an Na+-K+-ATPase, which pumps Na+ out of the cell and K+ into the cell and leads to a K+ gradient across the cell membrane
- Regulates heart and muscle contractions –maintains membrane potential
Regulation:
* Internal and external mechanisms
* Insulin and Beta 2 agonists shift K into cells
* Aldosterone alters uptake into cells and thus
urinary K levels
* Stimulation of alpha adrenoreceptors releases K from cells especially in the liver
Interesting facts about potassium: (for info)
The way that your blood is taken and handled can affect the potassium concentration in your blood sample
* clenched or pumped fist = ↑K
* If blood cells are damaged during sample collection they can burst and release potassium into the blood
* Some collection tubes contain potassium salts as a preservative
* Potassium can also be elevated if the specimen takes a long time to travel from your GP surgery
Hypokalaemia – too little K in ECF
Causes? (2)
S/S?
CAUSE:
1. External balance shift - increase in potassium
excretion in the kidneys
* Hyperaldosteronism
* Any disease which increases aldosterone e.g. Heart Failure, cirrhosis
* use of loop / thiazide diuretics
2. Internal balance shift where potassium moves into the cells, from the interstitium and blood
* Hypo-osmolality – water dragged into cells and
take K with it
* metabolic alkalosis – H must leave cells and
exchanged for K
* beta agonists promote the activity of the sodium-potassium ATPase
Signs and symptoms
* Abnormal heart rhythms (arrhythmias: flat T waves, ST depression)
* Muscle twitches
* Muscle cramps
* Severe muscle weakness, leading to paralysis
* Low blood pressure (hypotension)
* Bradycardia
* Lightheadedness or faintness
* Excessive urination (polyuria)
* Excessive thirst (polydipsia)
* Decreased GI motility»_space;>obstruction
Hyperkalaemia - too much K in ECF
Causes?
S/S?
- Advanced kidney disease
- A diet high in potassium
- Metabolic acidosis
- Tissue breakdown – crush injuries
- Medications: renin inhibitors, ACE inhibitors, angiotensin II receptor antagonists, selective aldosterone blockers, and potassium-sparing diuretics
Signs and symptoms
* Abnormal heart rhythms tight and contracted (arrhythmias: peaked T waves, ST elevations)
* …can lead to v-fib
* Low blood pressure (hypotension)
* Bradycardia
* Decreased urine output
* Profound muscle weakness
»>respiratory failure
* Increased GI motility»_space;>diarrhoea
Calcium
functions?
- Essential for muscle contraction, enzyme activity nerve function, blood clotting, cell division, healthy teeth and bones
- Helps to release neurotransmitters and hormones
- Absorbed through the intestines under the influence of activated vitamin D
- The amount of calcium in the blood is controlled by the combined actions of parathyroid hormone (PTH) and 1, 25-dihydroxyvitamin D (Vitamin D).
- Calcium is tested to help diagnosis and monitor a range of conditions relating to the bones, heart, nerves, and kidneys
- Other tests: phosphate, PTH, Vitamin D and
magnesium - Urine calcium may be requested if individuals have symptoms of kidney stones
Interesting facts about Calcium (for info)
- About 99% of calcium is found in the
bones - Blood and urine calcium measurements cannot be used to assess how much calcium is in the
bones. A test similar to an X-ray, called a bone density or ‘Dexa’ scan, is needed for this purpose.
Hypocalcaemia – too little Ca in the ECF
Causes?
usually from low protein conc of albumin
* Acute pancreatitis
* Iatrogenic parathyroid dysfunction
* Resistance to parathyroid hormone
* Hypoparathyroidism
* Hypomagnesemia (needed for PTH)
* Sepsis
* Multiple blood transfusions (additives chelate Ca e.g. EDTA)
* Elevated phosphorous
* Chronic Alcoholism
* Alkalosis
* Decreased vit D
* Chronic renal failure
* Cirrhosis
* Tissue injury – burns, Rhabdomyolysis, Tumour lysis syndrome
Hypocalcaemia – too little Ca in the ECF
S/S?
S – spasm
P – perioral parasthesia
A – anxious, irritable
S – seizures
M – muscle tone increased (smooth muscle)
TETANY
O – orientation impaired and confusion
D – dermatitis
I – impetigo herpetiformis (Rare)
C - Chvostek’s sign / Cardiomyopathy (Long QT
interval: takes longer for Phase 2 repolarisation)
* Weak bones
* Diarrhoea
Hypercalcaemia – too much Ca in ECF
CAUSE:
* Malignancy: Multiple myeloma, Breast
* Squamous cell carcinomas of the lungs (PTHrp mediated)
* Chronic Kidney disease
* Prolonged immobilisation
* Vit D overdose (food or supps – increase Ca
absorption)
* Hyperparathyroidism – PTH mediated release of
Ca from bones
* Chronic granulomatous diseases such as
tuberculosis or sarcoidosis
* Thiazide diuretics (slight increase reabsorption in DCT)
* Familial hypocalciuric hyperglycemia (defective calcium sensing receptor)
* High mortality rate if left untreated
Hypercalcaemia – too much Ca in ECF
Signs / symptoms
Dehydration – caused by resistance to ADH
and excess urination
Kidney stones
Constipation (voltage gated Ca channels less
likely to open harder to depolarise, true for
nerves (unexcitable) slower muscle
contraction thus constipation and abdominal
pain
Decreased deep tendon reflexes – muscle
weak
Bone pain
Anxiety and altered mental status
Phosphate ranges:
Normal range: 3.4 to 4.5 mg/dL
Hypophosphatemia: less than 2.5 mg/dL
Hyperphosphatemia: greater than 4.5 mg/dL
Phosphate
Role?
- Anion located in bone
- Bone and Teeth Health: component of
hydroxyapatite, the mineral that
provides strength and rigidity to bones
and teeth. - Energy Production: Phosphate is an
essential component ATP, ATP is
involved in various cellular processes,
including muscle contraction, nerve
impulse transmission, and metabolism - Cellular Signalling: activation of
enzymes and the regulation of gene
expression. It plays a role in cellular
communication and the coordination of
physiological processes - Phosphate also acts as a buffer for
hydrogen
Hypophosphatemia- Causes?
- Nutritional Deficiency
- Medications and Treatments: antacids, diuretics, and some
chemotherapy drugs, can lower phosphate levels. Additionally,
treatments like intravenous glucose, insulin therapy, and kidney
dialysis can contribute to hypophosphatemia - Alcoholism
- Hormonal Imbalances: hyperparathyroidism or growth hormone
deficiency - Kidney Disorders: renal tubular disorders, Fanconi syndrome, or
chronic kidney disease - Malabsorption Syndromes: celiac disease, Crohn’s disease, or
short bowel syndrome - Respiratory Alkalosis: Hyperventilation or respiratory disorders
that cause excessive elimination of carbon dioxide can cause
respiratory alkalosis, lowering phosphate levels
Hypophosphatemia- Signs and symptoms?
- Constipation
- Severe Muscle Weakness
- Bone and Joint Pain: increased
susceptibility to fractures - Irritability and Confusion
- Respiratory and Cardiac Issues: breathing
difficulties, cardiac abnormalities, such as
arrhythmias plus bradycardia and
hypertension - Fatigue and Malaise
- Numbness or Tingling: sensations of
numbness or tingling in the extremities - Loss of Appetite
Hyperphosphatemia- Causes?
- Hypoparathyroidism or overactive parathyroid glands (hyperparathyroidism)
- Excessive phosphate intake
- Certain medications: phosphate-based laxatives, phosphate-containing enemas, or certain antacids, can increase phosphate
levels. - Tumour lysis syndrome: this is a condition that can occur during cancer treatment when cancer cells break down rapidly, releasing
large amounts of phosphate and other substances into the bloodstream - Hypothyroidism: underactive thyroid function (hypothyroidism) can contribute to hyperphosphatemia by disrupting the balance of various minerals, including phosphate
- Rhabdomyolysis: this condition involves the breakdown of muscle tissue, which releases phosphate into the bloodstream
- Chronic kidney disease or acute kidney injury
