In the latest in our monthly series, Dr Nicolas Alexander asked readers to explain what was causing persistent diarrhoea in this otherwise well woman. Find out the answer below!
You see a 34-year-old female patient with a two-week history of diarrhoea, which she explains started suddenly a few days after returning from holiday in Switzerland. She volunteers no other symptoms, and denies any nausea, vomiting or abdominal pain. She also denies any recent stressors or change in diet. She hasn’t lost any weight or had any reduced appetite. No one else is unwell at home. She has no other past medical history and takes no regular medication.
She has been doing some internet research and is concerned about a possible ‘nasty bug’ causing her diarrhoea, as she drank water from a stream whilst hiking on holiday. Being the diligent GP you are, you furiously Google the cleanliness of water in Switzerland, and any known bugs in its waters or forests, and are relieved you can’t find anything.
Two weeks seems somewhat prolonged for a standard gastroenteritis. You reason it is likely to settle down in the near future but, given her concern, you agree to do a stool microscopy and culture and check for ova, cysts and parasites. You suspect it will be normal and might be a bit of IBS, so you discuss lifestyle, mindfulness and over the counter treatment options. She politely listens but you can sense she’s unconvinced.
Three weeks later the patient returns to see you with ongoing diarrhoea. Things have not changed much; she still does not have any other symptoms and feels well diarrhoea aside. Her weight has not changed, nor has her appetite and the diarrhoea continues though it still isn’t bloody. Her faecal tests were all normal and she has been trying to be mindful about managing her stress levels and has even tried some over the counter IBS tablets which haven’t helped. You scratch your head.
‘Given things are ongoing, let’s get some bloods done to see if there is an underlying cause for this,’ you reason. You work through the possible differentials (though you still think this is probably IBS and bloods will be normal) and settle on: FBC; U+E; LFT; CRP; coeliac screen. This seems a short list and since you’ve been doing some reading, you decide to check TFTs and bone profile too. You wonder about cancer, though it’s still early days. You decide to err on the side of caution and order a FIT test and faecal calprotectin in case you’re missing IBD. These don’t seem likely given her age and lack of weight loss, family history and the symptoms she describes.
Several days later you are reviewing her bloods and see that most have come back normal… except for one. Which do you think it is?
Answer
The abnormal test is thyroid function. She has a free T4 of 50 pmol/L and TSH <0.01 mU/L. You call the patient to go through the results which are consistent with hyperthyroidism. She’s unsurprised. ‘Oh yes, my mum had that!’. You now ask a thyroid focused history and several of her responses confirm your suspicions: ‘Yes, I have been feeling more jittery now you mention it… And yes I have also felt hot and hungrier… I was surprised I wasn’t putting on weight!’ She denies any visible tremor or any neck swelling.
After a call to your friendly endocrinologist on call, she is duly started on some carbimazole and booked into the endocrinology clinic for follow up.
You see the patient again a few months later for a different issue and she remembers you as ‘that clever doctor’ after seeing the endocrinologist – they had commented that while this isn’t an uncommon presentation, many don’t think to check for hyperthyroidism until a lot later. She reports symptoms have settled and on looking at her latest clinic letter, you notice her thyroid function has normalised.
Learning points
It is important to consider hyperthyroidism in a young person with new diarrhoea. Thyroid hormones act on most organs in the digestive tract and digestive symptoms may be the only manifestation of hyperthyroidism. Up to 25% of patients have mild to moderate diarrhoea with frequent bowel movements.
Asking about any family history may have elucidated her mother’s hyperthyroidism. We can sometimes be caught out by more closed and focused questioning (eg, IBD and colon cancer in the case of abdominal pain).
Although the diarrhoea may be the only symptom of hyperthyroidism, a symptoms review is helpful as it may also present with tremor, increased appetite, stable weight despite this increased appetite and feeling hotter and sweatier than those around you.
As with a lot of general practice, it’s important we ask the right questions, be open minded about possibilities, and be thorough. This isn’t always easy with the myriad possibilities to a lot of what we see.
Cases like this shouldn’t induce self-flagellation for not getting the right answer straight away but rather be used as a means of broadening our approach. This is probably the most important take away in the current highly pressured climate of primary care in which we practice.
Dr Nicolas Alexander is a GP and GP trainer in North East London
Oviva’s fully remote Tier 3 Weight Management programme
The patient who returns to England 2 weeks ago from a holiday in Switzerland and denies any ‘recent stressors or change in diet’ is not being entirely honest, as she has recently travelled (stresssful), and been in a different country (different diet), unless she really did not notice she was in a diferent country, so there was no point in going at all! I am pretty sure mountain streams can also have giardia. And travel could have caused urinary infection, upsetting bowels.
Price of everything ‘in Schweiss’ could cause a little intestinal hurry.