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Medical School > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

Osmolar gap

  1. Calculated by
  2. Normal
  3. What might a large osmolar gap indicate
A
  1. 2[Na + K] + Urea + Glucose
  2. <10
  3. Presence of high levels of e.g. ethanol
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2
Q

Compensation - level at which this is definitely occurring

  1. CO2 in metabolic acidosis
  2. CO2 in metabolic alkalosis
  3. HCO3 in respiratory acidosis
  4. HCO3 in respiratory alkalosis
A
  1. <4.5 kPa
  2. > 6.0 kPa
  3. > 30 mmol/L
  4. <24 mmol/L
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3
Q

Acute respiratory acidosis results

A

CO2 high

pH low

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4
Q

Chronic resp acidosis with compensation results

A

CO2 high
pH normal/ near normal
HCO3 high

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5
Q

Hypoventilation

  1. Causes (3 types)
  2. Typical features (3)
  3. Blood tests (5)
  4. Other tests (2)
  5. Treatment (2)
A
  1. Neuromuscular disease (e.g. GBS, myasthaenia gravis), lung disease (e.g. COPD), decreased central respiratory drive (e.g. trauma, brainstem disease, encephalitis)
  2. Confusion, peripheral vasodilation (from raised ICP), coma
  3. FBC, U+E, TSH, ABG, toxicology
  4. CXR, lung function
  5. Treat cause, consider respiratory support
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6
Q

Acute respiratory alkalosis - presentation

A

CO2 low

pH high

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7
Q

Chronic respiratory alkalosis w/ compensation -presentation

A

CO2 low
pH normal / near to normal
HCO3 low

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8
Q

Hyperventilation

  1. Causes (CNS, lung, hypoxia, drugs, endocrine, other)
  2. Clinical features
  3. Blood tests
A
  1. CNS (meningitis / stroke / anxiety / trauma), lung (pneumothorax, pneumonia, pulmonary oedema, PE), hypoxia (severe anaemia), drugs (salicyclates, catecholamines) endocrine (pregnancy, hyperthyroidism), other (sepsis, liver / heart failure / mechanical ventilation)
  2. Hand numbness, tingling round mouth, light headed, tachycardic
  3. ABG, U+E, TSH
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9
Q

Anion gap

  1. Calculated using
  2. Purpose

Anion gap range:

  1. Low
  2. Normal
  3. High
  4. High anion gap - significance
  5. High anion gap - examples
  6. Normal anion gap - significance
  7. Normal anion gap - examples
  8. Normal anion gap - aka
A
  1. [Na + K] - [Cl - HCO3]
  2. To investigate if a metabolic acidosis is due to exogenous or endogenous acid
  3. Low: <12 mmol/L
  4. Normal: 12-16 mmol/L
  5. High: >16 mmol/L
  6. Metabolic acidosis from exogenous acid build up
  7. Lactate (type a) shock, sepsis, hypoxia, type b) metformin), ketones (DKA, alcohol), acid poisoning (methanol, salicyclates e.g. aspirin), urate (renal failure)
  8. Means metabolic acidosis from endogenous acid build up or bicarb loss e.g. GI / renal loss
  9. GI HCO3 loss (diarrhoea, fistula), renal tubular acidosis, hyperchloraemia, Addison’s disease (high K+)
  10. Hyperchloraemic metabolic acidosis
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10
Q

Metabolic acidosis

  1. Cause (3 broad types)
  2. Blood tests
  3. Treatment in severe cases
A
  1. Increased H+ (Lactic acidosis, ketoacidosis, some drugs), failure to excrete H+ (renal), bicarb loss (GI or renal loss)
  2. FBC, U+E, ABG, lactate, serum osmolality, glucose
    Loss of bicarb - GI loss or renal loss
  3. Bicarb replacement
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11
Q

Metabolic alkalosis

  1. Cause (3 broad types)
  2. Clinical features
  3. Blood tests
  4. Management (3)
A
  1. H+ loss (vomiting, diuretic therapy), HCO3 build up (ingestion), endocrine imbalance (cushing’s, hyperaldosteronism, fludrocortisone)
  2. Hypoventilation (compensation), hypocalcaemia symptoms (numbness/tingling of lips/peripheries, muscle cramps, seizures, bradycardia)
  3. ABG, U+Es, renin, aldosterone, cortisol
  4. Treat cause, replace fluid, replace electrolytes
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12
Q

Hyponatraemia - causes

  1. Tests (4)
  2. Hypovolaemic - usual urine osmolality
  3. Urinary Na >30 (from kidneys - causes)
  4. Urinary Na <30 (from elsewhere)

Euvolaemic (Na normal, H20 gained)

  1. Urinary Na >30, urinary osmolality >100 (from kidneys)
  2. Low urinary Na/Osmolality (from elsewhere)
  3. Hypervolaemic/Oedematous - urine osmolality + Na
  4. Causes
  5. Management
A
  1. Assess hydration status, plasma + urinary osmolality, urinary Na+
  2. Urine osmolality >400
  3. Thiazide/loop diuretics, Addison’s, osmotic diuresis
  4. Extra-renal loss - D+V, burns, sweating
  5. SIADH (urine osmolality > 500), hypothyroid
  6. H2O intoxication
  7. Urine osmolality >100, Na <30
  8. Water excess - CCF, low albumin (cirrhosis / nephrotic syndrome), IV dextrose
  9. Treat cause, sodium correction (saline if hypo/Eu, fluid restrict if oedematous)
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13
Q

Hypernatraemia

  1. Tests
  2. Causes - euvolaemic
  3. Hypovolaemic - producing small concentrated urine
  4. Not producing small amounts concentrated urine (2)
  5. DI - osmolalities
  6. Management - general
  7. If euvolaemic
  8. If hypovolaemic
A
  1. Hydration status, osmolality (urine/serum), fluid deprivation (DI)
  2. Iatrogenic from lots of crystalloid, Na+ drugs
  3. Normal response - dehydration, D+V, burns
  4. Abnormal response - osmotic diuresis (DKA), DI
  5. Plasma high, urine low
  6. Treat cause, sodium correction
  7. Dextrose
  8. Saline
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14
Q

Hypokalaemia

  1. Causes - increased renal excretion
  2. Intestinal K+ loss
  3. Increased cellular uptake (3)
  4. Signs (2)
  5. ECG changes
  6. Management - if K+ >2.5
  7. If K+ <2.5
A
  1. Diuretics, endocrine e.g. Cushing/Conn, RTA, low Mg2+
  2. D+V
  3. Salbutamol, insulin, alkalosis
  4. Muscle weakness, hypotonia
  5. U wave, small/absent T, long QT, ST depression
  6. Sando K tablets
  7. KCl in 0.9% NaCl over 6 hours
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15
Q

Hyperkalaemia

  1. Causes - less excretion
  2. Excess K+ load (2)
  3. Increased cellular release (2)
  4. Signs
  5. ECG changes
  6. Management
A
  1. AKI, CKD, Addison’s, NSAIDs, spironolactone, ACE-i
  2. Iatrogenic, blood transfusion
  3. Acidosis, tissue breakdown e.g. rhabdo/haemolysis
  4. Generalised muscle weakness, flaccid paralysis + paraesthesia in hands/feet, lethargy, confusion, palpitations
  5. Absent P, long PR, broad QRS, tall tented T
  6. Calcium gluconate 10 10 (if ECG changes / K+ >6.5), Actrapid Insulin Dextrose, Salbutamol Nebulisers
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16
Q

Hypocalcaemia

  1. Causes - increased renal excretion
  2. Phosphate/PTH levels
  3. PTH-related
  4. Phosphate/PTH levels
  5. High deposition/low uptake
  6. Phosphate/PTH levels
  7. Signs
  8. ECG changes
  9. Tests
  10. Management - severe
  11. Mild, from low Vit D
  12. CKD-associated low Vit D
  13. Low calcium + vit D
A
  1. Loop diuretic, CKD, rhabdo/TLS
  2. High PO4, high PTH
  3. Low/pseudo PTH, low Mg2+, cinacalcet
  4. High PO4, low PTH
  5. Bisphosphonates, low vit D
  6. Low PO4, high PTH
  7. Tetany e.g. Trousseau/Chvostek signs, perioral paraesthesia, chronic then depression/cataracts
  8. QT prolongation
  9. Renal function, PTH, phosphate, magnesium
  10. Calcium gluconate
  11. Colecalciferol
  12. Alfacalcidol
  13. Adcal-D3
17
Q

Hypercalcaemia

  1. Causes - low excretion
  2. High release from bones (check ALP)
  3. Excess PTH - causes, + PO4 levels
  4. Other
  5. Signs
  6. ECG changes
  7. Tests
  8. Management
A
  1. Thiazide diuretics
  2. Bony metastasis if ALP high, myeloma if ALP normal, sarcdoid, thyrotoxicosis
  3. Primary (PO4 low) / tertiary (PO4 low/normal) hyper-PTH
  4. Excessive Vit D intake
  5. Bones, groans, stones, psychic moans, corneal calcification, HTN (same in low Mg2+)
  6. Short QT
  7. Renal function, ALP, PTH, phosphate, specific
  8. Treat cause, replace fluid deficit + keep hydrated, IV bisphosphonate if severe
18
Q

Hypomagnesaemia

  1. Causes - excess loss
  2. Lifestyle
  3. Concominant low electrolytes
  4. Management
A
  1. Diuretics, diarrhoea, DKA
  2. Poor nutrition/alcoholism
  3. Happens if potassium/calcium low
  4. Replace (do 1st before any other electrolyte abnormalities)
19
Q

Hypophosphataemia

  1. Causes - deficiency
  2. High hormone level
  3. Lifestyle
  4. Management
A
  1. Vit D deficiency
  2. Primary hyperparathyroidism
  3. Refeed syndrome/poor nutrition/alcoholism
  4. Replace (do not give if low Ca2+ / oliguric)

Medical School (28 decks)

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