Labs + Dx

Question 1

causes for resp alkalosis

Answer 1

• CNS mediated hyperventilation
  
  • Increased intracranial pressure
  • Cerebrovascular accidents
  • Psychogenic
• Hypoxia-mediated hyperventilation
  
  • Altitude
  • Anaemia
  • V/Q mismatch
• Pulmonary
  
  • Congestive cardiac failure
  • Mechanical hyperventilation
  • Pneumonia
  • Pulmonary emboli
• Sepsis
• Toxin-induced hyperventilation
  
  • Nicotine
  • Salicylate
  • Xanthines

Question 2

• Causes of respiratory acidosis:

Answer 2

• Airway obstruction
  
  • aspiration
  • Bronchospasm
  • Drug-induced CNS depression
  • Hypoventialtion of CNS or muscular origin
  • Pulmonary disease
  • Kyphoscoliosis
  • Lung disease
  • Neuromuscular disorders
  • Obesity

Question 3

causes for metabolic alkalosis

Answer 3

• Administration of bases
  
  • Antacids
  • Dialysis
  • Milk-alkali syndrome
• Gastrointestinal acid loss
  
  • Protracted vomiting or nasogastric suction
• Renal bicarbonate retention
  
  • Chronic hypercapnia
  • Hypochloraemia
  • Hypokalaemia
• Urinary acid loss
  
  • Adrenogenital syndrome
  • Bartter’s syndrome
  • Cushing’s syndrome
  • Diuretics
  • Licorice
  • Primary Hyperaldosteronism
• Volume contraction

Question 4

• Causes of a non-anion gap metabolic acidosis (abnormal bicarbonate loss or chloride retention):

Answer 4

• Drugs
  * Acetazolamide
  * Acidifying agents
  * Cholestyramine
  
  • Gastroinestinal bicarbonate loss
    
    • Diarrhoea
    • Pancreatic fistula
  • Rapid hydration with normal saline
  • Renal bicarbonate loss
    
    • Renal tubular acidosis
    • Uretoenterostomy

Question 5

• Causes of a low anion gap (<6):

Answer 5

• Increased Unmeasured cations
  
  • Hypercalcaemia
  • Hypermagnesaemia
  • Lithium intoxication
  • Multiple myeloma
• Decreased unmeasured anions
  
  • Dilution
  • Hypoalbuminaemia
• Artefactual Hyperchloraemia
  
  • Bromism
  • Iodism
  • Hypertriglyceridaemia

Question 6

AGMA - catmudpiles

Answer 6

• Carbon monoxide, Cyanide
• Alcohol, alcoholic ketoacidosis
• Toluene
• Metformin, Methanol
• Uraemia
• Diabetic Ketoacidosis
• Paracetamol, Propylene glycol, Paraldehyde
• Iron, Isoniazid
• Lactic acidosis
• Ethylene glycol
• Salicylates, Starvation ketoacidosis

Question 7

• Exogenous agents associated with an elevated osmolar gap:

Answer 7

• Acetone
  
  • Ethanol
  • Ethylene glycol
  • Glycerol
  • Glycine
  • Isopropyl alcohol
  • Mannitol
  • Methanol
  • Propylene glycol

Question 8

• Non-toxicological causes of an elevated osmolar gap:

Answer 8

• Alcoholic Ketoacidosis
  
  • Chronic renal failure
  • Diabetic Ketoacidosis
  • Hyperlipidaemia
  • Hyperproteinaemia
  • Massive Hypermagnesaemia
  • Severe lactic acidosis
  • Shock
  • Trauma and burns

Question 9

AGMA - goldmark

Answer 9

G
Glycols
Ethylene Glycol
Propylene Glycol
Antifreeze, coolant
Antifreeze, food preservatives, e-cigartettes, tobacco products, IV infusions such as benzodiazepines, coffee products, sweeteners

O
Oxoproline
Chronic acetaminophen ingestion

L
L-Lactate
Type A Lactic Acidosis
(hypoperfusion)
Type B Lactic Acidosis
(normal perfusion)
Other
Hypovolemia, cardiac failure, sepsis, cardiac arrest
Metformin toxicity, mitochondrial dysfunction, DKA, cyanide, inborn errors of metabolism
Liver failure, sepsis, malignancies

D
D-Lactate
Short bowel syndrome, propylene glycol ingestion, DKA

M
Methanol
Antifreeze, solvents, fuel

A
ASA

R
Renal Failure
Uremia
Renal failure, Toluene inhalation

K
Ketoacidosis
Ketones
Diabetic ketoacidosis, starvation states, chronic alcoholism

Question 10

AGMA - KULT

Answer 10

• K – Ketones (DKA, starvation, alcoholism)
• U – Uremia (Kidney failure)
• L – Lactate (L and D lactate)
• T – Toxins (ASA, Methanol, Ethylene Glycol, Toluene)

Question 11

DDx for LOW ANION GAP (<6)

Answer 11

• lab error
  
  • Increased Unmeasured cations = high Lithium, Mg+, Ca+, cationic IgG paraprotein
  • Decreased unmeasured anions = Dilution / Hypoalbuminaemia
  • severe normal anion gap (hyperchloremic) metabolic acidosis
  • ingestion of substance w positive charge = halide anions such as fluoride, bromide and iodide

Question 12

DDX for non-anion gap metabolic acidosis

Answer 12

(abnormal bicarbonate loss or chloride retention):

* Gastroinestinal bicarbonate loss = Diarrhoea / Pancreatic fistula
* Rapid hydration with normal saline = volume expansion
* Renal bicarbonate loss = Renal tubular acidosis  = proximal HCO3 reabsorption is impaired (ammonia retention)