Hyponatremia Flashcards
What is the safe limit for rising sodium in hyponatremia
8-10mmol/L in 24 hours
Definition of hyponatremai
<135 mmol/L Na
What conditions is hyponatremia ass with
Heart disease
Liver cirrhosis
Neurological disorders
Grading of hyponatremia levels
- Mild - 130-135
- Moderate - 125-129
- Profound <125
Symptoms of hyponatremia
Asymtpomatic
Headache
N+V
Muscle cramps
Lethargy
Signs of hyponatremia
Disorientation
- Seizures
- Coma
- Cerebral oedema
- Death
What base management of hypoNa off
Clinical presentation AND levels
Causes of hyponatremia
Reduced renal free water clearance
Pseudohyponatremia - hypertriglyceridaemia
Sodium depletion
Excess water intake
SIADH
Reduced clearance free water -> hyponatremia causes
- Hypovolaemia
- Drugs
- Renal failure
- Portal hypotension and ascites
- Hypoabuminaemia
- Sespsis and vascular leak
- Central salt wasting
- Fluid sequestration
- Cardiac failure
- Nephrotic syndrome
- Hypothyroidism
- SIADH, nephrogenic SIADH
- Hypoadrenalism
Sodium depletion causes
- Renal loss
- Diuretics
- Salt wasting/ central SW
- Nephropathy
- Hypoaldrenalism
- Extra renal loss - Gut los
Excess water intake -> hyponatremia causes
- Dipsogenic DI
- Sodium free hypo-osmolality IV solutuons
- Dilute infant feeding formulas
- IV therapy
Essentuak criteria for SIADH
Hyponatremia
Clinical euvolaemia
Serum osmolality <275 Osm/kg
Urine osmol >100mOsm/kg
Urina Na .30mmol/L
RULE OUT - see card
What need to rule out in diagnosing SIADH
No recent diuretic
Absence of:
Hyotension, hypovolaemia
Non osmotic AVP release
Oedema
Adrenal, thyroid and renal insufficiency
Why is SIADH diangosis of exclusion
Because management is fluid restricition which is opposite treatment to most other causes of hyponatremia
Drugs that cause SIADH
- SSRI
- Carbamazepine
- Phenothiazines
- TCAs
- Cyclophophamide
- Opiates
- Vincristine
- NSAIDs
- Clofibrate
- PPIs
CNS causes of SIADH
Inflammatory
Tumour
Infection
SIADH causes - chest
Infection
Structural
Inflammatory eg sarcoidosis
Small lung cell carcinoma
Bedisde investigations for SIADH
Urine investigations - sodium and osmolality
Plasma
Osmolality
LFTs, bone panel
TFTs
9am cortisol
Radiology for SIADH
- CXR
- Consider CT chest, abdo , pelvis if SIADH confirmed and no cause identified
What can cause non hypotonc hyponatremia
Hyperglycaemia
Causes of urine osmolality ,100mOsmol/kg
- Primary polydipsia
- Inappropriate IV fluids
- Low solute intake eg
- beer potamania syndrome - high volumes of beer (low solute) → hyponatremia
Causes of hyponatremia where serum .100mOsmol/kg but urine <30mmol/L
- Low effective atrial volume HF
- Cirrhosis/portal HPTN
- Nephrotic syndrome
- Hypoalbuminaemia
- Third space loss
- GI loss
- Prev diuretic use
Causes of hyponatremia where serum .100mOsmol/kg but urine >30mmol/L
Diuretics or ACE
Mangement hyponatremia
Exclude hyperglycaemia
Treat w hypertonic saline if any severe symptoms over 20 mins Otherwise stop non essential pareneteral fluids + meds ass w hyponatremia + treat underlying cause
If clinically well dont try and correct sodium levels
