Hyponatremia – or low sodium levels in blood – is the bane of my existence as a Hospitalist Doc! Add that to the list of other pesky issues to deal with – like vertigo, headaches, generalized weakness, mild confusion, etc.. The pathophysiology of various causes of Hyponatremia makes it convoluted to remember – Instead, I find it easier & faster to recall the common culprits of hyponatremia first & see if the patient’s clinical picture fits!
While ‘SIADH‘ is a well-known condition in the context of hyponatremia, which stands for ‘Syndrome of Inappropriate ADH secretion‘. I also use ‘SIADH‘ to remember & recall causes of low sodium levels quickly and logically:
S – SIADH, Salt-wasting
I – Increased Intake of Water (i.e. Polydipsia) or Alcohol ( i.e. Beer Potomania)
A – Adrenal Insufficiency, AKI (& CKD)
D – Dehydration
H – Heart failure, Hepatic disease, Hypothyroidism*
*Hypothyroidism as a cause of low sodium is rare and is seen in severe hypothyroid cases
The beauty of the above mnemonic is it also helps you remember the various mechanisms of Hyponatremia.
Here’s a useful graphic I created to help remember the basics and diagnosis of Hyponatremia causes:
