More on Hyponatremia

Regarding hyponatremia, which accompanied my symptoms of nausea, extreme fatigue, drymouth, weakness and the beginning of some confusion back in September, the following sentiments are ones I can identify with:

Yin:

Yang:

My symptoms turned out to be those of Isolated ACTH Deficiency (IAD). In terms of rarity, IAD is a rare disorder, listed in the Rare Diseases Database by NORD (National Organization of Rare Diseases). To put one number on it, this paper says,

The incidence of IAD in adult patients is not well understood due to its rarity (7). A single Japanese cohort study estimated its prevalence at 3.8-7.3 per 100,000 (8). Between 1969 and 1994, more than 300 cases were reported in Japan; thus, IAD may not be as rare as indicated by the scarcity of literature (9).

In terms of my suspicion that the hyponatremia that occurred contemporaneously with my nausea, fatigue, weakness, etc. symptoms should have been paid attention to as a marker of something, now hyponatreima is being pointed to more and more as a marker for IAD that oncologists treating with immunotherapy should look for. This 2019 "Letter to the Editor" about hyponatremia in Endocrine Journal (coming out 4 months after my episode), says,

Hyponatremia can be a powerful
predictor of the development of
isolated ACTH deficiency associated
with nivolumab treatment 

and

Our cases highlight the importance
of comparing serum Na levels before and
during treatment, and measuring ACTH and cortisol
levels in patients with hyponatremia during
nivolumab treatment.

Regarding my NA levels showing hyponatremia, the oncologist on my team said it meant nothing. The practice nurse on my team argued with me that whether it even was hyponatremia -- he said it wasn't. Whereas a nurse substituting for my PCP at the time, told me my hyponatremia was serious and I should report to the ER in the morning if I couldn't bring my sodium levels up by binging on salt that night. That told me that hyponatremia was a big deal, and a few days later I did the simple google search that told me to tell my oncology team that I was approaching or in an adrenal crisis.

I'm aware now that seeing my PCP, or NP subbing for him, can be a helpful backstop to my oncology team.