Tuesday, 13 December 2011

Let's Get Technical, Baby

Apologies for my lack of posting lately! I have been doing exams. They are now over, and my new excuse is that it's Christmas (in case you hadn't noticed). But, as of a phone call from the hospital on Wednesday last week, I have been meaning to give an update on my health. In short: my thyroid stimulating hormone levels are still normal, but I will have to start new treatment shortly... because I have high levels of the TSH alpha subunit.

"The what-now? What in god's name is that?" I hear you cry.

Don't cry.

My endocrinologists have always been cagey whenever I've tried to get them to explain what the alpha subunit actually is,* although in fairness, my shrewd personal judgement leads me to believe that this is probably less because it's a dark and terrible secret and more because they're not paid to teach biochemistry.

Anyway, the combined powers of Wikipedia and Google have provided me with the answer: it turns out that thyroid-stimulating hormone (TSH) is a dimer; a chemical compound of two identical or similar monomers: in this case, the alpha subunit, and the beta subunit. No-one wants to get bogged down in the detail, so at this point I promise not to use the word "glycoprotein" without extreme provocation.**

So: TSH is made of two kinds of stuff. And as it turns out, TSHomas (pituitary tumours which produce TSH) have a bit of a habit of producing more of the alpha subunit than would normally be expected. Normally you would expect the ratio of free alpha subunit to TSH to be less than 1. Before my surgery in April, my ratio of alpha subunit to TSH was 14:1. Currently, it's 7:1.

Obviously, 7:1 is better than 14:1. However, it is equally obviously Not Quite Right.*** Consequently it seems likely that the TSHoma is still active, and even though my total thyroid-stimulating hormone levels are within normal limits, it may still be secreting some TSH as well. Active tumour = growing tumour.

So I'm going to start having injections of some kind of somatostatin analogue again. I haven't really written about this up to now (it's on my list, promise) but for three months before my operation last year I was having monthly injections of Somatuline, the brand name for lanreotide. It's a synthetic form of a hormone naturally released by the hypothalamus,**** which inhibits the production of TSH and growth hormone, and which is used to treat pituitary adenomas which are releasing either one of those hormones. If you're lucky, it can shrink the tumours a bit - at the least, it should check their growth and can also help to make their structure less fibrous, which makes it easier for surgeons to chop them up.

It's also super expensive. When my GP first looked up how much it cost after my endocrinologist had requested a prescription, he laughed in a slightly manic way for about five minutes at the price. Awkward.

I'm going to start the injections again, probably in January, for three months, to assess whether they shrink the tumour at all and whether they bring down the high levels of alpha subunit in my blood. I'm not massively looking forward to starting again - the injections mess with your body a bit, last time I felt nauseous for three days after the first one, and they're a bit of a hassle because you have to order the injections a week in advance from the pharmacy, then drop them off at your GP's because they have to be kept in the fridge. The injections sting, they have to use a massive needle because the stuff is so thick, and you end up with a lump in your hip - basically it's injected under the skin where it sits and slowly decreases in size over the month as it gets absorbed into your system.

On the plus side, having these injections should (in theory) get rid of the last of my symptoms. And that would be very nice. I am really quite bored now of my hair falling out/heart randomly getting overexcited/headaches. As for what happens after three months, who knows. The injections are a possible long term treatment option although they are an expensive hassle and they're quite likely to give you gallstones sooner or later. So that brings you back to surgery/radiotherapy. Oi vey.


*Apart from an excellent title for some kind of spy film.

**Incidentally, the α subunit is thought to be the effector region responsible for stimulation of adenylate cyclase

***I must stop using these technical medical phrases.


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