At the end of April, I performed the 24-hour urinary excretion of aldosterone test, eating a high-salt diet for three days followed by urine collections over a 24-hour period. The 'salt loading' was achieved by obtaining salt tablets (yes, such a thing exists) from a pharmacy which led to a little comedy as the pharmacist wasn't sure what the dose should be. She wasn't familiar with this test (probably no one is) so she decided to call the doctor (it's good that they have contact details for cases like these) and established that I have to take 2 grams three times a day. As each tablet contained 500 mg salt, this meant 4 tablets each time, 12 a day, 36 overall. I also went to the kibbutz clinic to pick up a container for the urine.
On Monday morning I started with these pills. They are, as one might expect, salty, but swallowing them wasn't a problem. I ensured that I drank a large amount of fluid during the day. On Tuesday, I was able to swallow the first three pills each time, but the fourth caused a small amount of nausea. This got slightly worse on Wednesday, but I swallowed all the pills like a good boy.
The urine collection started on Wednesday morning, not including the first urination. By 9:30 am, I had already collected about 1.3 litres which had me worrying as the container held only 2 litres. I picked up a larger (4 or 4.5 litre) container from the clinic that had come since my visit on Sunday. I continued to work, take pills, drink and urinate. By Thursday morning I had collected 3.7 litres - apparently the usual amount is about 2 litres, so obviously something was happening! I was told to shake the container (in order to mix the liquid) then pour off an amount into the usual container for urine samples. I also had yet another blood test on Thursday morning.
The idea of the salt loading is that it is supposed to shut down the production of aldosterone and so any found in the urine means that the body is over-producing. The blood test showed that my sodium and potassium levels were as usual, meaning that something is continuing to maintain the balance of these elements (that are connected to water retention and blood pressure).
After a week, I received the results of the urine test - 33.9 nmol - but again, I couldn't figure out from the internet what this means: it's a normal level but I suspect that 'normal' does not take into account the salt loading. Again on Sunday morning, my doctor telephoned me and confirmed that this level is considered high after the salt loading, but not extremely high. The next step is a CT of the area - I'll shortly make the booking. The hypothesis of primary hyperaldosteronism is strengthening, although I have to admit that some of the treatments mentioned in the linked article don't sound appealing.
Although I didn't feel any ill effects from the salt loading (apart from the mild nausea when taking the pills), I have just downloaded the data from my CPAP machine for the past two weeks, and the days of the salt loading (and the day after) show a relatively high number of central apneic events. Interesting. It's a shame that I couldn't tell the doctor this (he can contact me but not vice versa) - I'll have to remember this for our next conversation.
I've had a viral throat infection for the past few days and haven't felt particularly well during the days; most nights are problematic when the painful swallowing wakes me. Despite this, the CPAP data doesn't show any change and the number of apneic events has actually been very low over the past few days. Isn't that strange: something that medically is extremely minor makes me feel unwell, but I feel nothing from something that is medically significant.
