Chemical Pathology I - Sodium and Water Flashcards
Define Normal, Mild, Moderate, Severe, Dangerous Hyponatremia
Plasma Na level (mmol/L) Normal: 135-145 Mild: 130-135 Moderate: 125-130 Severe: 115-125 Dangerous <115
Symptoms of Hyponatremia at Moderate, Severe and Dangerous levels
Moderate: Anorexia, Nausea, Vomiting, Abdominal pain
Severe: Agitation, Confusion, Hallucination, Mental impairment, Incontinence
Dangerous: Seizure, Coma, life-threatening
2 classifications of hyponatremia
1) By Hydration
- Hyper-, Eu-, Hypovolemia
2) By serum Osmolality
- Hypotonic in true hyponatremia
- Normotonic in pseudohyponatremia
- Hypertonic - hyperglycemia, IV mannitol
Explain hypovalemic, euvolemic and hypervolemic true hyponatremia
Hypovalemic: Low water, Very low Na
Euvolemic: Normal Na, High water (dilutional)
Hypervolemic: Very high water, high Na
3 steps in assessment of Hyponatremia
1) Serum osmolality
2) Paired spot urine Na before Na replacement
3) Extracellular fluid volume
3 outcomes after the 1st step in assessment of hyponatremia
Assess serum osmolality
1) Normal = Hyponatremia due to Hyperlipidemia or Hyperproteinemia
2) Increased osmolality: Hypertonic Hyponatremia due to Hyperglycemia
3) Decreased osmolality»_space; Do paired spot urine Na before Na replacement
How to use Paired spot urine Na to differentiate causes of Hyponatremia with decreased serum osmolality
1) >20 mmol/L:
a) Hypovolemia: Renal sodium loss
b) Euvolemia: Chronic water overload
2) <20 mmol/L
a) Edema: Renal sodium retention
b) Hypovolemia: Extrarenal Na loss
c) Euvolemia: Acute water overload
Serum osmolality normal + Hyponatremia. Dx?
Psuedohyponatremia due to Hyperlipidemia (Triglyceride >50mmol/L)
or
Hyperproteinemia (Total protein >150 g/L)
Serum osmolality Increased + Hyponatremia. Dx?
Hypertonic hyponatremia
Due to Hyperglycemia
Hyponatremia + Serum osmolality decreased + Spot urine Na >20 mmol/L
Extracellular volume: Hypovolemia.
Dx?
Renal sodium loss
- Diuretics
- Addison’s disease
- Salt losing nephritis
Hyponatremia + Serum osmolality decreased + Spot urine Na >20 mmol/L
Extracellular volume: Euvolemia.
Dx?
Chronic** water overload
SIADH Drugs Chronic renal failure Hypothyroidism Cortisol deficiency
Hyponatremia + Serum osmolality decreased + Spot urine Na < 20 mmol/L
Extracellular volume: Euvolemia.
Dx?
Acute** water overload
- Increased water intake
- Drugs
- Hypothyroidism
- Cortisol deficiency
- Renal failure
Hyponatremia + Serum osmolality decreased + Spot urine Na < 20 mmol/L
Extracellular volume: Hypovolemia
Dx?
Extrarenal Na Loss
- Vomiting
- Diarrhea
- Skin loss
Hyponatremia + Serum osmolality decreased + Spot urine Na < 20 mmol/L
Extracellular volume: Edema
Dx?
Renal sodium retention
- Cirrhosis
- Cardiac failure
- Nephrotic syndrome
Most common form of hyponatremia in hospitalized patients?
Euvolemic Hyponatremia
- SIADH
- Post-operation: Pain and stress/ iatrogenic (excess fluid replacement)
- Endocrine: Hypothyroidism, Hypopituitism, Cortisol deficiency
8 medications that can cause SIADH
CCOOVAF
Carbamazepine
Cyclophosphamide
Oral hypoglycemics
Oxytocin
Vincristine
Amitriptyline
Fluphenazine
Ectopic production of ADH causing SIADH? (4)
Duodenal cancer
Pancreatic cancer
Small cell lung cancer
Thymic cancer
Pulmonary diseases that can cause SIADH?
Acute asthma
Atelectasis
Infections
Pneumothorax