Clinical Biochem 2 Flashcards
In a volume assessment, what effects can happen in a depleted volume
- postural hypotension –> inc HR
- Dry mouth
- Poor skin turgor test
In a volume assessment, what would volume overload look like?
- inc resp. rate
- wheezy chest
- inc jugular venous pressure, >3 cm above sternal angle
- positive hepatojugular reflex (push chest down, if jugular veins stay up = +)
- Edema (swelling)
What BUN (blood urea nitrogen) to creatinine ratio mean dehydration? Why?
Ratio greater than 0.08+
- bc the kidneys reabsorb BUN more than creatinine when patient is dehydrated
- give IV replacement fluids
Sodium (mostly ECF)
Reference range?
Primary function?
Low levels + symptoms?
High levels + Symptoms?
Reference range?
135-145 mmol/L
Primary function?
- regulation of fluid volume (by thirst, ADH, renal)
- major cation of ECF
Low levels + symptoms?
- <120 mmol/L Hyponatremia
- Hypotonic ECF –> water flows into cell(burst)
- Nausea, vomiting, anorexia
High levels + Symptoms?
- 160mmol/L+ hypernatremia
- Hypertonic ECF –> water flows out of cell
- Seizures, thirst, lethargy, coma, irritability
In Hypotonic-hyponatremia, define HYPOvolemic and causes
Hypovolemic (low)
- due to water loss from different areas of the body
Causes:
- GI losses
- Skin losses
- Lung losses
- Renal losses
- Diuretics
In Hypotonic-hyponatremia, define ISOvulemic and causes
Isovolemic (normal)
- dilutional –> water accumulation without sodium accumulation (low Na levels)
Causes
- Water intoxication
- Renal failure
- Symptom of inappropriate ADH
In Hypotonic-hyponatremia, define HYPERvolemic and causes
hypervolemic (high)
- smaller inc in body sodium and bigger inc in total body water –> diluted sodium in the body
Causes
- congestive heart failure
- Liver damage
- Nephrosis
in NON-hypotonic hyponatremia, explain isotonic hyponatremia, give an example
Isotonic
- administration of isotonic, sodium free, Intravenous solution
- eg. 5% dextrose
in NON-hypotonic hyponatremia, explain hypertonic hyponatremia, give an example
hypertonic
- administration of hypertonic, sodium free, Intravenous solution
- eg. mannitol
What can non-hypotonic hyponatremia treat? (mannitol)
hypernatremia
What does Hypernatremia with LOW total body sodium and LOW fluid volume indicate?
more water loss than sodium loss
What does Hypernatremia with normal total body sodium indicate?
water loss WITHOUT sodium loss
What does Hypernatremia with high total body sodium indicate?
uncommon (due to infusion/ingestion of highly hypertonic solutions
Potassium (mostly ICF)
Reference range?
Primary function?
Low levels + symptoms?
High levels + Symptoms?
Reference range?
- 3.5-5 mmol/L
Primary function?
- Primary intracellular cation
- Regulates nerve and muscle excitability
Low levels + symptoms?
- <2.5 mmol/L Hypokalemia
- bradycardia (low HR)
- CRAMPS, weakness, ORTHOSTATIC hypotension, paralysis
High levels + Symptoms?
- 8+mmol/L Hyperkalemia
- VFIB, bradycardia (low HR), hypotension, CARDIAC ARREST, muscle weakness, paralysis
What are some causes of hyperkalemia? Hypokalemia?
Hypokalemia
- lack of intake
- excessive renal loss
- ICF shft
- Excessive GI fluid loss
Hyperkalemia
- Excessive intake
- Impaired renal function
- Redistribution to ECF
Explain pseudohyperkalemia
When RBCs hemolyze –> release potassium
- high false reading
- can be caused by needle size too small
Chloride
Reference range?
Primary function? Regulated by?
Low levels + causes?
High levels + causes?
Reference range?
- 100-108 mmol/L
Primary function?
- major extracellular anion
- Primary passive role ( with sodium: fluid balance) (with CO2: acid-base balance)
- Regulated by sodium and bicarb
Low levels + causes?
- <75 mmol/L hypochloremia
causes:
- GI FLUID LOSS
- metabolic alkalosis
- renal losses (from Na loss)
- indirect caused by drugs
High levels + causes?
- 125+ mmol/L hyperchloremia (rarely on its own)
Causes
- accompanied by NA AND WATER RETENTION
- metabolic acidosis
Magnesium (ICF)
Reference range?
Primary function?
Low levels + symptoms, caused by?
High levels + Symptoms, caused by?
Reference range?
- 0.8-1 mmol/L
Primary function?
- neuromuscular function (ATP), bone formation, enzymatic function
Low levels + symptoms, caused by?
- <0.5 mmol/L
- weakness, increased reflexes, IRREGULAR HEART, CNS changes, confusion
- Caused by GI or renal losses
High levels + Symptoms, caused by?
- 1.5+ mmol/L
- bradychardia, HEART BLOCK, confusion, DEACREASE TENDON REFLEX, weakness, HYPOCALCEMIA, decreased clotting mechanism
- Caused by Renal dysfunction or Mg overload
What are large doses of Mg used for? What is the dose? What is the risk, antidote?
Prevention and treatment of seizures
- Mg 4g bolus + 1-2 g/hr infused via 40g/L intravenous solution
Risk
- very high dose = respiratory depression/arrest
- antidote: calcium injection
Calcium
Reference range, location?
Primary function?
Low levels + symptoms, caused by?
High levels + Symptoms, caused by?
Reference range?
2.1-2.6 mmol/L
- 99% in bone
- 1% ECF (40% bound to albumin, 15% complexed with citrate, bicarb, phosphate, 45% free ionized active form)
Primary function?
- nerve impulse transmission, muscle contract, AV & SA Node, blood coagulation, endocrine, bone metabolism
Low levels + symptoms, caused by?
- <1 mmol/L
- Numbness, myalgias, tingling to tetany, cardiac arrhythmias, hypotension, seizures
- Caused by: disorders of Vitamin D metabolism or parathyroids hormone
High levels + Symptoms, caused by?
- 3+ mmol/L
- GI symptoms, lethargy, confusion, acute renal failure
- Caused by: malignancies, primary hyperparathyroidism, drug
What do changes in albumin effect?
changes protein binding
- in turn affects both total serum calcium and free ionized calcium
What is the relation between the drop of albumin and serum calcium
every 10g/L drop of albumin, calcium drops by 0.2 mmol/L
What does alkalosis & acidosis refer to in terms of protein binding and unbound (ionized) calcium
Alkalosis: high protein binding = lower unbound (ionized) calcium
Acidosis: lower protein binding = higher unbound (ionized) calcium
Phosphate (ICF)
Reference range?
Primary function?
Low levels + symptoms, caused by?
High levels + Symptoms, caused by?
Reference range?
0.8-1.6 mmol/L
Primary function?
- intracellular anion in bone & muscle
- role in metabolism + bone formation
Low levels + symptoms, caused by?
- < 0.3 mmol/L
- muscle weakness, rhabdomyoliss, haemolysis, platelet dysfunction, seizures
- Caused by: reduced intake, intracellular shift, increased excretion
High levels + Symptoms, caused by?
- 2.4+ mmol/L
- calcium phosphate deposition (calcification) in soft tissue, osteomalacia, accompanying hypocalcemia and hyperparathyroidism
- Caused by: excessive intake with renal disease
What is the relationship between calcium and phosphate?
If one is high then the other is low
Explain false hypercalcemia (high calcium)
turner kit left on too long
