Is this bad news?

[Mybonnielad]

After a lengthy bout of gastroenteritis, I had a blood test that showed low-sodium levels (130, when the norm is 133 - 146)
The doctors rang and want another blood test tomorrow. Am I right in thinking there is something really wrong? I have health anxiety anyway, so stressing out about this.

Sodium levels (and probably others) are likely to be low when your body is essentially "cleansing" itself. Try not to stress but get the blood test done. You're just slightly outside the norm according to your post so is probably just a double check to be safe.

Perhaps though speak to your doctor about what may be helpful for your health anxiety

Your bloods (including sodium levels) are bound to be off considering you’ve had an electrolyte disturbance due to the gastroenteritis. It’s not extremely worrying in the slightest & should correct itself upon you being able to take fluids in again.