If you have compared your own symptoms with those listed on the Symptoms page of this site, and you believe you may have hypopituitarism, proceed with caution. GPs may not be trained to spot the condition and may believe it, incorrectly, to be extremely rare. (In fact BBC’s Inside Health programme has estimated that there are between half a million and a million undiagnosed sufferers in the UK.) You may need to come armed with research to support your case. Many people have found it helps if they ask to see their medical notes. You can then check what investigations have already been done, and what have not. Remember that you have a right to see your notes.
A comprehensive list of the tests required to diagnose hypopituitarism can be found on Endobible. It is important to be aware of these as you may have to ask for some of them specifically. If you have had a previous head injury, the recent guidance from the British Neurotrauma Group may be useful evidence to produce. A further point that might persuade your GP is that NICE has finally undertaken to include the hypopituitarism risk in its head injury guideline update, due out May 2022.
Below are some notes about the diagnosis of various possible pituitary deficiencies. They are not exhaustive, and it is recommended that you do your own research. The Pituitary Foundation and the Mayo Clinic site are useful sources.
Provocative tests (also described as dynamic or stimulation tests) are needed to diagnose this. The most common initial test is the short synacthen test. The Pituitary Foundation adds this proviso: “Please note: for patients with symptoms that may suggest cortisol deficiency that a ‘pass’ on a SST, may not always mean that cortisol deficiency is excluded, and that with persisting symptoms, referral to an endocrinologist is recommended, where testing may be carried out with alternatives such as the glucagon test or insulin stress test.” The insulin stress test is the best test. (The glucagon test is not completely reliable for diagnosing cortisol deficiency.) If you have difficulty in persuading your GP, you could point out the risk that if you have undiagnosed cortisol deficiency, you may suffer a life-threatening adrenal crisis. Some patients have found that if they buy the day curve cortisol test from a private laboratory and get an abnormal result, their GPs are more easily persuaded. Details on the Pituitary Foundation website.
Growth hormone deficiency
Measuring IGF-1 levels is often used as a diagnosis tool. However, normal levels do not rule out growth hormone deficiency, and if your symptoms suggest it you should push for a dynamic test.
Recommended dynamic tests are the ‘gold standard’ insulin stress test, the glucagon stimulation test and the GHRH Arginine test. Again, it may be hard to persuade your GP as these tests are costly. As a preliminary you could ask to have your triglycerides tested. These are often tested at the same time as cholesterol as a standard health precaution for the over-50s. High triglycerides can accompany growth hormone deficiency and could be a warning sign.
It is worth noting that the NICE criteria for authorizing growth hormone replacement are as follows:
Recombinant human growth hormone (somatropin) treatment is recommended for the treatment of adults with growth hormone (GH) deficiency only if they fulfil all three of the following criteria.
They have severe GH deficiency, defined as a peak GH response of less than 9 mU/litre (3 ng/ml) during an insulin tolerance test or a cross-validated GH threshold in an equivalent test.
They have a perceived impairment of quality of life (QoL), as demonstrated by a reported score of at least 11 in the disease-specific 'Quality of life assessment of growth hormone deficiency in adults' (QoL-AGHDA) questionnaire.
They are already receiving treatment for any other pituitary hormone deficiencies as required.
Sex hormone deficiency
Normally your FSH/LH levels will be tested, and if you are a man, your testosterone levels also. You may be told that if your FSH/LH levels are in the normal range (1.5-12.4 U/L) this excludes secondary hypogonadism (i.e. sex hormone deficiency with a hypothalamo-pituitary cause) but in fact according to the standard textbook Principles and Practice of Endocrinology and Metabolism, K L Becker “In secondary hypogonadism, LH and FSH levels will be in the normal or subnormal range despite a low total or free testosterone level.”
Testosterone tests should be performed between 7am and 10am (Harvard Health Publishing) as levels fluctuate throughout the day. Total testosterone levels can be misleading as part of the testosterone will be bound to sex hormone binding globulin (SHBG) and not bioavailable. According to the Harvard site, a careful evaluation could involve testosterone measurements on more than one day, as well as tests for levels of hormones related to testosterone.
This table shows the normal levels of testosterone at various ages. Your GP may claim your testosterone is within range, without realising that for your age, the level should be higher than your test result.
Insert Vermeulen table here
To diagnose this your Thyroid Stimulating Hormone (TSH) and your thyroxine (T4) levels will be tested. Your triiodothyronine (T3) levels should also be tested but this is not routinely offered. If you have secondary/central hypothyroidism (i.e. of thalamo-pituitary cause) your TSH will generally be low, but normal or even high levels are sometimes seen. The Thyroid UK website is a source of information and support.
The amount of urine your produce will be measured and your anti-diuretic hormone (ADH) levels will be tested. See the Mayo Clinic’s information.
You will have a blood test to check your prolactin levels and possibly an MRI scan. Verywell health has a useful article.
MRI scans are another diagnostic tool to pick up any abnormality in your pituitary gland and you may be offered one.
Letter from Society of Endocrinology page 1
Letter from Society of Endocrinology page 2