Hyponatremia due to SIADH.

Resolved question:
what would cause an 84 year old male to have low sodium (125), low chloride (91) low anion gap (9.6) and low cal. serum osmolality (257)??
He is on a 700 cc water restriction and 3 grams of sodium per day per his kidney doctor. This has made his sodium raise up to 130 but there has got to be an underlying cause.
He had a stroke in October but no lasting effects. He feels very weak and collapsed in a restaurant and was then transported to a hosptial where he was a patient for 5 days at the end of January. They gave him tolvaptan once, stabilized him and sent him on his way. He has blood drawn every 5 days to check sodium level. He was diagnosed with a staph infection in his urinary tract on March 14th so was on 2 different antibiotics and took his last round yesterday. He is my father and my fear is that he will die before someone figures this out. He has a primary care doctor, a kidney doctor and a urologist. But here I am looking for answers on the internet.
Thanks you
Vanessa Steed

Submitted: 4 Days
Category: Nephrologist

Expert:  Dr. Sree Bhushan Raju replied 4 Days.

Hello Ms Steed,

Elderly people are more prone for Hyponatremia (low sodium). Patients with stroke are vulnerable for hyponatremia due to a possible condition called " SIADH".

As a first step we need to rule out hypothyroidisma nd low cortisol conditions before calling it as SIADH. I advice him to undergo thyroid function tests once. And if possible, serum cortisol test also can be done. Tolvaptan is not really required for him at this juncture as sodium level already nearer to 125 meq/ lit. Give him fluids around 1200 ml per day. If there is a risk of infections then prophylactic antibiotics are also needed.

There is no reason to be overly worried about the sodium levels. This is a common scenario and I am sure your Doctors can easily manage. The patient is more likely to get UTIs frequently. Check his prostate evaluation done. Ask him to eat well and drink water more frequently (if he is taking oral feeds).

So for now I recommend - ruling out hypothyroidism, do a S.Cortisol. Wait and watch approach. Do not rapidly correct the sodium levels. No need to chase the 'sodium' levels as long it is not too low. Remember this is a common scenario and can be easily managed.

Hope this helps
Feel free to ask followups


best,
Dr. Sree Bhushan Raju
MD, DM (AIIMS), DNB, FISN, FICP, FIACM

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