By the time type 2 diabetes is diagnosed, up to one person in five already has damage at the back of the eye. Work backwards from that damage, and the disease turns out to have started at least four to seven years before anyone gave it a name. For all those years a light was on: a thirst that never quite went, one more trip to the loo at night, a tiredness blamed on work.
Think of it like a car's dashboard. When a warning light comes on, the car is not broken. It is communicating. Tape over the light and the problem continues.
We are good with tape. Painkillers for the headache, antacids for the reflux, caffeine for the fatigue, sleeping pills for the insomnia. Each one silences the signal and leaves whatever sent it alone.
Carmakers began swapping gauges for warning lights in the mid-1930s, and the lights earned a nickname: idiot lights. A gauge shows trouble coming. A light only comes on once it has arrived. A body is kinder than a dashboard. Most of what follows are gauges, and gauges can be read early.
The lists of "signs you should never ignore" leave out the other half. Most dashboard lights are a loose fuel cap. When 1,000 patients at one clinic were followed for three years, they brought in 567 new symptoms: tiredness, headaches, dizziness, weight loss and ten more of the same kind. A physical cause was found for 16% of them.
So the skill is telling the oil-pressure light from the fuel cap. This article does it for twelve common signals your body sends. For each one: what it usually is, the clue that changes the picture, and the test that settles it.
1. Tiredness that sleep does not fix
Usually. Too little sleep, or too much strain for too long. A hidden illness is the exception.
The clue. Weeks of decent sleep change nothing, and the tiredness has company. Breathlessness and pale skin point one way. Feeling cold, constipation and dry skin point another. Thirst that never lets up points a third.
The test. A blood count with ferritin, the thyroid hormones, blood sugar and B12. Ferritin is the one to ask for by name. It measures the iron you hold in store, and the store can run low while the blood count still looks normal.
That is one of the few places where "my tests were fine" and "something is wrong" are both true. Why Am I Always Tired: When Chronic Exhaustion Has a Cause That Sleep Can't Fix takes the causes one at a time.
2. Weight that changes for no reason
Losing it is the one to act on. Grief or a lost job can strip weight off a person, and so can a quiet illness. Across 25 sets of findings, weight loss with no explanation was tied to ten different cancers, and from the age of 60 it crosses the line at which UK guidance says to investigate.
The clue. If the weight is falling while your appetite grows, your heart pounds and you feel hot when nobody else does, the thyroid is running fast.
Gaining it slowly is rarely a mystery. A sudden change is different, and the first suspect is the bathroom cabinet. In 257 tests of medicines on 84,696 people, some antidepressants, antipsychotics and diabetes tablets each added up to about three kilos. A slow thyroid adds weight too, along with feeling cold, constipation and dry skin. So does the menopause, which tends to put it around the middle.
The scales are a blunt gauge in any case. Pooled across 31 papers and more than 300,000 adults, waist divided by height picked out the people at risk of diabetes, high blood pressure and heart disease better than body mass index did, and better than waist size alone. The NHS turns it into one rule: keep your waist to less than half your height.
The test. A thyroid blood test, a list of everything you take, and a tape measure.
3. A gut that complains after every meal
Usually. Gas. Carbohydrates that the small gut fails to absorb travel on to the bacteria further down, which ferment them. When 30 people with irritable bowel syndrome spent three weeks eating few of those fermentable carbohydrates, their symptom scores fell by half against three weeks on an ordinary diet.
Some gas is simply the machinery running. Ten volunteers ate their usual food plus 200 g of baked beans and had every bit of gas collected for a day. The totals ran from 476 to 1,491 millilitres each. Two days without fibre cut the typical figure from 705 to 214. The bacteria were doing their job, and the dial is on the plate.
So the first experiment happens there. Onions, beans, wheat, apples and milk are the common culprits, and a meal built on meat, fish or eggs holds almost nothing for the bacteria to ferment. Foods That Upset Your Gut: What's Real and What's Personal sorts the suspects.
The clue. Bloating that comes with weight loss, or with blood, or with a change in your bowels that lasts for weeks, needs checking. So does bloating that never lifts at all.
The test. A blood test for coeliac disease, which affects at least 1 person in 100. It only works while you are still eating gluten, so take the test before you change the diet. In the UK only 36% of the people who have it have been told, which leaves about half a million who have not.
4. Mood that swings without a reason
Usually. Sleep. Pooled across 19 experiments and 1,932 people, lost sleep damaged mood more than it damaged thinking or movement. The second suspect is the calendar: the weeks before a period, and the years around the menopause, both bring mood swings of their own.
The clue. Swings that arrive with weight loss, a racing heart and a dislike of warm rooms point to an overactive thyroid. A mood that is flat most of the day, every day, for more than two weeks points to depression. Reach out for help.
One popular theory deserves a correction. About 95% of the body's serotonin is made outside the brain, most of it in the gut, and from that comes the claim that a troubled gut means a serotonin shortage in the head. Serotonin made in the gut stays out of the brain, which makes its own. The Science of Serotonin: Everyday Habits That Lift Your Mood has what does reach it.
The test. The thyroid hormones, and an honest count of your sleep.
5. Appetite that changes
More of it, usually. A short night. Pooled across 11 experiments, people whose sleep was cut short ate about 385 calories more a day.
The clue. Hungry all the time and losing weight anyway. That pairing is the mark of an overactive thyroid, and weight loss without trying is on the list for diabetes too.
Less of it, usually. Stress, a passing illness, or a new medicine. Appetite that stays away for weeks while the weight drops is sign 2 again.
The test. The thyroid hormones and blood sugar.
6. Skin that changes
Skin has four signals that are seldom explained to the person wearing them.
A dark, velvety patch in the folds of the neck, armpit or groin. It looks like dirt and it will not wash off. It goes with high insulin: among 1,133 young patients, those who had the patches were about twice as likely to have type 2 diabetes. This is the insulin you can see.
Acne along the jaw and chin in an adult woman, with periods that come late or skip, and dark hair in new places. Together they point to polycystic ovary syndrome, which the NHS now calls PMOS and which affects at least one woman in ten.
Itching with nothing to look at. Usually it is dry skin, or something the skin has touched. Less often, an itch all over with no rash is a sign from the thyroid, the liver or the kidneys.
A mole that is new, or an old one that changes. This is the one skin sign with a deadline. Ordinary moles are small, round, one colour, and stay as they are. A mole that changes size, shape or colour, has an uneven edge or more than one colour, or starts to itch, bleed or crust needs looking at soon.
The test. Blood sugar for the first, hormones for the second, a general blood panel for the third, and a trained eye for the fourth.
7. Headaches that keep coming back
Usually. Something ordinary and repeated. Skipped meals, too little water, alcohol, poor posture, tired eyes, and the painkillers themselves, which cause headaches when taken too often.
A headache that returns on schedule is being set off by something on a schedule. Unexpected Causes of Your Headaches and How to Find Yours is the way to find it.
The clue. A headache that starts suddenly and is the worst of your life. One that comes with a stiff neck and a high temperature, with weakness or numbness, with confusion, or after a blow to the head. Those are emergencies. Skip the search engine.
The test. For the ordinary kind there is none, and hunting for one is dear. At the clinic with the 567 symptoms, each physical cause found for a headache cost $7,778 in tests, in 1989 money. The tool is a diary: when it came, what you had eaten and drunk, how you had slept.
8. A craving for ice
This is the most specific light on the board.
Craving things that are not food has a name, pica, the Latin for magpie, a bird believed to eat almost anything. The commonest form is ice: chewing it by the trayful. Of 262 adults being treated for low iron, 45% had pica, and for 87% of them it was ice. In another count, 56% of anaemic people chewed ice compulsively, against 4% of people without anaemia.
Nobody is sure why. One test gives a hint: chewing ice sped up reaction times in anaemic people and did nothing for the healthy. The ice may be a cold slap for a brain running short of oxygen.
Low iron has quieter clues as well: a sore tongue, cracks at the corners of the mouth, and legs that will not keep still at night.
The test. A blood count and ferritin. In the group of 262, every person with pica said it had gone within three weeks of their first iron treatment.
Meat, fish and poultry carry haem iron, which the body absorbs better than the iron in plants, and lean meat and seafood are its richest sources. And iron is one to test for, never to guess at. Too much does harm.
9. Bad breath that brushing does not fix
The popular explanation is the stomach. The counted one is the mouth.
At one breath clinic, 2,000 people were examined one after another. A cause in the mouth was found for 76% of them: a coated tongue alone in 43%, the gums in 11%, both in 18%. A cause elsewhere in the body turned up in 4%. And 16% had no bad breath at all. They were sure they did.
That is the gap between a symptom and a sign. Symptom is Greek for "that which befalls": an accident. Medicine keeps the word for what you feel and saves sign for what somebody else can see, measure or, in this case, smell. Those 16% had the symptom without the sign. By the same rule, about half of the twelve signs here are symptoms.
Usually, then. The back of the tongue, where bacteria sit under a coating and make sulphur gases.
Clean your tongue once a day with a . In one small test it cut those gases by about 40%, against a third for a toothbrush, though the drop had gone within half an hour. So it's a daily habit and not an all-day fix.
The clue. Breath that smells sweet and fruity, like pear drops or nail-varnish remover. That is acetone. On a ketogenic diet it is expected and harmless: twelve adults eating ketogenic meals had three and a half times the acetone on their breath within twelve hours. Off such a diet, fruity breath with thirst, peeing and feeling sick is an emergency.
10. Thirst, and trips to the loo
Usually. Salty or spicy food, a sweaty day, alcohol or caffeine.
The clue. Thirst that water does not answer, with more peeing than your drinking explains. When sugar builds up in the blood, the kidneys pass it out, and it takes water with it. You drink, you pee, and you stay thirsty. Tiredness, blurred vision and cuts that are slow to heal belong to the same picture.
This is the light from the opening, the one that stays on for years. Almost 1.3 million people in the UK are thought to have type 2 diabetes without knowing it.
The test. HbA1c, a blood test that gives your average blood sugar over the last two to three months. An does it by post, from a sample you take yourself.
If it comes back high, food is the strongest lever you hold. Pooled across eight tests and 264 people with type 2 diabetes, 57% of those on a low-carbohydrate diet were in remission at six months, against 31% on the comparison diets. By twelve months the figures were too thin to call. How to Fix Blood Sugar Spikes Naturally covers low-carb, keto and carnivore eating in detail.
Peeing often without the thirst is a different light. With burning or urgency it points to a urine infection. In men, with a weak stream and nights broken by trips to the loo, it points to the prostate.
11. Hair that sheds, nails that break
Hair and nails are a record of the recent past, not the present day.
Hair. A shock to the body, such as a fever, an operation, childbirth or a crash diet, can switch up to 70% of growing hairs into their resting phase at once. They stay put for a while, and the fall comes two to four months later, long after the cause has been forgotten. The odd part is what pushes them out: the new hairs growing underneath. This kind of hair fall is a sign of regrowth. It tapers back to normal over six to nine months in most cases, and the only treatment is patience.
Shedding that goes on, or thins the hair all over, is worth a test for iron and for the thyroid. Both are on the short list of causes.
Nails. They grow about three and a half millimetres a month, which makes each one a slow diary. A groove running across a nail marks a time when growth stalled, during a serious illness, say. Measure from the cuticle to the groove and you can estimate the date. These are Beau's lines, described in 1846.
A nail that has flattened or dipped into the shape of a spoon is a sign of low iron. Fingertips that have grown rounded and bulbous, the nail curving over the end, have been read as a sign of illness since Hippocrates, who is also credited with the first description of pica. Two of these lights are about 2,400 years old. Clubbed fingertips point to the lungs and the heart.
The eyebrow. Thinning of the outer third of the eyebrow has a name, Hertoghe's sign, and a nickname, Queen Anne's sign, after portraits of Anne of Denmark. It can appear when the thyroid is badly underactive. It also appears with eczema and with ordinary ageing, and nothing in the record suggests the queen had a thyroid problem. Treat it as a nudge towards a test.
Biotin. The supplement most marketed for hair and nails has almost nothing behind it. A search for evidence found 18 cases where it helped, and every one involved a person with an underlying condition. Real deficiency is rare. It was first found in chicks fed raw egg white, which contains a protein that locks biotin away.
It has a cost as well. Six healthy adults took an ordinary over-the-counter biotin supplement for a week, and 9 of the 23 blood tests of one common type came back wrong, thyroid tests among them. If you take it, say so before any blood test.
12. Night sweats
Usually. A warm room, a heavy duvet, or a drink. Alcohol is on the short list of causes, and so are several medicines, some antidepressants, steroids and painkillers among them.
In women in their forties and fifties, the usual cause is the menopause. The band of temperature the body will tolerate narrows, partly because oestrogen has fallen, so a small rise sets off a full-scale dumping of heat. Among 3,302 women followed for years, frequent hot flushes or night sweats lasted a median of 7.4 years.
Light nightclothes, a cool bedroom, and fewer of the known triggers: spicy food, caffeine, hot drinks, smoking and alcohol.
There is reassurance in the counts. Depending on who is asked, between 10% and 60% of people report night sweats, and those who do live as long as those who do not.
The clue. Sweats that soak the sheets and come with weight loss, a fever or a cough. Get that combination looked at.
The test. For sweats on their own, none. With the clue, expect blood tests.
A thirteenth light, for men
It is left off these lists because it is awkward to bring up.
Among 9,457 men aged 55 and over, those who developed erection problems were 25% more likely to have a heart attack, a stroke or a similar event in the years that followed. The size of the risk was in the range that goes with smoking, or with a family history of heart attack. The paper's own word for it was harbinger.
One explanation is plumbing. The same build-up narrows every artery in the body, and the narrowest pipes complain first.
The test. Blood pressure, cholesterol and blood sugar. A at home covers the first. The embarrassing conversation is the cheap one.
The blood test you already have
If you have ever had a blood count, you hold more information than you were shown how to use.
The count reports the size of your red blood cells. Cells that are smaller than normal point to iron. Cells that are larger than normal point to B12 or folate. If your results show either, the direction of the search is already in hand.
B12 has a grey zone of its own. Under official UK guidance, a result below 180 nanograms per litre confirms a deficiency and a result above 350 makes one unlikely. Anything in between is labelled "possible vitamin B12 deficiency" and calls for a second test. A "normal" in that band is still an open question.
Two common medicines lower B12 over the years: metformin, taken for blood sugar, and the tablets that reduce stomach acid. B12 comes from meat, fish, eggs and dairy.
Ask for the numbers as well as the verdict.
The pattern behind the list
Read the twelve again and the same names keep turning up.
Iron sits behind signs 1, 8 and 11. The thyroid is in 1, 2, 4, 5, 6 and 11. Blood sugar is in 1, 5, 6, 9, 10 and the thirteenth. The hormones of the cycle and the menopause are in 2, 4, 6 and 12. Sleep is in 1, 4 and 5. Medicines are in 2, 5, 7 and 12.
Six causes, twelve lights. A small number of upstream failures produce a large number of downstream signals, which is why the list is shorter than it looks.
It also makes the testing simple. A blood count with ferritin, the thyroid hormones and HbA1c cover three of the six. B12 and the coeliac test catch the two commonest things the six leave out. The other three need no laboratory: a calendar for the cycle, a count of your sleep, and a list of your medicines. It requires knowing what to ask for.
Three lights on this list are never a fuel cap, and they skip the queue: a sudden headache that is the worst of your life, fruity breath with thirst and sickness, and stools that are black or dark red. Those are for today.
For the rest, time is the gauge. The NHS draws its line at three weeks for a cough and for a mouth ulcer, and it works as a rule for any light with no clue of its own: new, still there after about three weeks, or getting worse.
And if everything comes back clean? Go back to the clinic with the 567 symptoms. Five in six had no physical cause to find, and where the outcome was recorded, just over half got better. A clean result is an answer: it crosses off the oil-pressure lights and leaves the fuel caps, which sleep, food and time can reach.
Noticing a gauge move at all is a skill, and it can be trained. Read Your Body's Signals: The Sense Most People Let Fade shows how.
The light in the opening stayed on for four to seven years because it was easy to live with. The easy ones are the ones to check.
Take the tape off one light this week. Pick the one that has been on longest, and ask for its test.
Noticed something new, and unsure what to do about it? How to Respond to a Symptom Without Ignoring It or Panicking — a calm way through a new symptom: what needs care today, what can wait, and what is worth watching.
Wondering whether you are short of a vitamin or a mineral? Why Every Nutrient Deficiency Checklist Says You're Low — who runs low in what, and the test that shows it.
Know someone who has been ignoring the same symptom for a year? Send them this, with the number of their sign.
Tried something here, or got a question it didn't answer? Write to us at contact@allforlife.club. Your questions shape the next articles.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If you notice any of the warning signs described above, or a symptom is new, lasting or getting worse, get checked.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
Sources
Harris MI, Klein R, Welborn TA, Knuiman MW (1992). Onset of NIDDM occurs at least 4–7 yr before clinical diagnosis. Diabetes Care 15(7):815–819. doi.org/10.2337/diacare.15.7.815
Wikipedia. Tell-tale (automotive). en.wikipedia.org
Kroenke K, Mangelsdorff AD (1989). Common symptoms in ambulatory care: incidence, evaluation, therapy, and outcome. The American Journal of Medicine 86(3):262–266. doi.org/10.1016/0002-9343(89)90293-3
Houston BL, Hurrie D, Graham J, et al. (2018). Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials. BMJ Open 8(4):e019240. doi.org/10.1136/bmjopen-2017-019240
NHS. Unintentional weight loss. nhs.uk
Nicholson BD, Hamilton W, O'Sullivan J, Aveyard P, Hobbs FR (2018). Weight loss as a predictor of cancer in primary care: a systematic review and meta-analysis. British Journal of General Practice 68(670):e311–e322. doi.org/10.3399/bjgp18X695801
NHS. Overactive thyroid (hyperthyroidism): symptoms. nhs.uk
Domecq JP, Prutsky G, Leppin A, et al. (2015). Drugs Commonly Associated With Weight Change: A Systematic Review and Meta-analysis. The Journal of Clinical Endocrinology & Metabolism 100(2):363–370. doi.org/10.1210/jc.2014-3421
NHS. Underactive thyroid (hypothyroidism): symptoms. nhs.uk
NHS. Menopause: symptoms. nhs.uk
Ashwell M, Gunn P, Gibson S (2012). Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obesity Reviews 13(3):275–286. doi.org/10.1111/j.1467-789X.2011.00952.x
NHS. Obesity: diagnosis. nhs.uk
Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG (2014). A Diet Low in FODMAPs Reduces Symptoms of Irritable Bowel Syndrome. Gastroenterology 146(1):67–75.e5. doi.org/10.1053/j.gastro.2013.09.046
Tomlin J, Lowis C, Read NW (1991). Investigation of normal flatus production in healthy volunteers. Gut 32(6):665–669. doi.org/10.1136/gut.32.6.665
Monash University. High and low FODMAP foods. monashfodmap.com
NHS. Bloating. nhs.uk
NHS. Coeliac disease. nhs.uk
NHS. Coeliac disease: diagnosis. nhs.uk
Coeliac UK. About coeliac disease. coeliac.org.uk
Pilcher JJ, Huffcutt AI (1996). Effects of Sleep Deprivation on Performance: A Meta-Analysis. Sleep 19(4):318–326. doi.org/10.1093/sleep/19.4.318
NHS. PMS (premenstrual syndrome). nhs.uk
El-Merahbi R, Löffler M, Mayer A, Sumara G (2015). The roles of peripheral serotonin in metabolic homeostasis. FEBS Letters 589(15):1728–1734. doi.org/10.1016/j.febslet.2015.05.054
Al Khatib HK, Harding SV, Darzi J, Pot GK (2017). The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis. European Journal of Clinical Nutrition 71(5):614–624. doi.org/10.1038/ejcn.2016.201
NHS. Type 2 diabetes: symptoms. nhs.uk
Kong AS, Williams RL, Smith M, et al. (2007). Acanthosis Nigricans and Diabetes Risk Factors: Prevalence in Young Persons Seen in Southwestern US Primary Care Practices. The Annals of Family Medicine 5(3):202–208. doi.org/10.1370/afm.678
NHS. Acanthosis nigricans. nhs.uk
NHS. Polyendocrine metabolic ovarian syndrome (PMOS): symptoms. nhs.uk
World Health Organization. Polycystic ovary syndrome. who.int
NHS. Itchy skin. nhs.uk
NHS. Melanoma skin cancer: symptoms. nhs.uk
NHS. Headaches. nhs.uk
Wikipedia. Pica (disorder). en.wikipedia.org
Barton JC, Barton JC, Bertoli LF (2010). Pica associated with iron deficiency or depletion: clinical and laboratory correlates in 262 non-pregnant adult outpatients. BMC Blood Disorders 10:9. doi.org/10.1186/1471-2326-10-9
Hunt MG, Belfer S, Atuahene B (2014). Pagophagia improves neuropsychological processing speed in iron-deficiency anemia. Medical Hypotheses 83(4):473–476. doi.org/10.1016/j.mehy.2014.07.016
NHS. Iron deficiency anaemia. nhs.uk
National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. ods.od.nih.gov
Quirynen M, Dadamio J, Van den Velde S, et al. (2009). Characteristics of 2000 patients who visited a halitosis clinic. Journal of Clinical Periodontology 36(11):970–975. doi.org/10.1111/j.1600-051X.2009.01478.x
Wikipedia. Signs and symptoms. en.wikipedia.org
NHS. Bad breath. nhs.uk
Seemann R, Kison A, Bizhang M, Zimmer S (2001). Effectiveness of mechanical tongue cleaning on oral levels of volatile sulfur compounds. The Journal of the American Dental Association 132(9):1263–1267. doi.org/10.14219/jada.archive.2001.0369
NHS. Diabetic ketoacidosis. nhs.uk
Musa-Veloso K, Likhodii SS, Cunnane SC (2002). Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals. The American Journal of Clinical Nutrition 76(1):65–70. doi.org/10.1093/ajcn/76.1.65
NHS. Thirst. nhs.uk
Diabetes UK. How many people in the UK have diabetes? diabetes.org.uk
Diabetes UK. What is HbA1c? diabetes.org.uk
Goldenberg JZ, Day A, Brinkworth GD, et al. (2021). Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ 372:m4743. doi.org/10.1136/bmj.m4743
NHS. Urinary tract infections (UTIs). nhs.uk
NHS. Benign prostate enlargement: symptoms. nhs.uk
DermNet. Telogen effluvium. dermnetnz.org
NHS. Hair loss. nhs.uk
Yaemsiri S, Hou N, Slining MM, He K (2010). Growth rate of human fingernails and toenails in healthy American young adults. Journal of the European Academy of Dermatology and Venereology 24(4):420–423. doi.org/10.1111/j.1468-3083.2009.03426.x
Wikipedia. Beau's lines. en.wikipedia.org
Wikipedia. Nail clubbing. en.wikipedia.org
Wikipedia. Sign of Hertoghe. en.wikipedia.org
Patel DP, Swink SM, Castelo-Soccio L (2017). A Review of the Use of Biotin for Hair Loss. Skin Appendage Disorders 3(3):166–169. doi.org/10.1159/000462981
Wikipedia. Avidin. en.wikipedia.org
Li D, Radulescu A, Shrestha RT, et al. (2017). Association of Biotin Ingestion With Performance of Hormone and Nonhormone Assays in Healthy Adults. JAMA 318(12):1150–1160. doi.org/10.1001/jama.2017.13705
NHS. Night sweats. nhs.uk
Freedman RR (2014). Menopausal hot flashes: mechanisms, endocrinology, treatment. The Journal of Steroid Biochemistry and Molecular Biology 142:115–120. doi.org/10.1016/j.jsbmb.2013.08.010
Avis NE, Crawford SL, Greendale G, et al. (2015). Duration of Menopausal Vasomotor Symptoms Over the Menopause Transition. JAMA Internal Medicine 175(4):531–539. doi.org/10.1001/jamainternmed.2014.8063
NHS. Menopause: things you can do. nhs.uk
Mold JW, Holtzclaw BJ, McCarthy L (2012). Night Sweats: A Systematic Review of the Literature. The Journal of the American Board of Family Medicine 25(6):878–893. doi.org/10.3122/jabfm.2012.06.120033
Thompson IM, Tangen CM, Goodman PJ, et al. (2005). Erectile Dysfunction and Subsequent Cardiovascular Disease. JAMA 294(23):2996–3002. doi.org/10.1001/jama.294.23.2996
Montorsi P, Ravagnani PM, Galli S, et al. (2005). The Artery Size Hypothesis: A Macrovascular Link Between Erectile Dysfunction and Coronary Artery Disease. The American Journal of Cardiology 96(12B):19M–23M. doi.org/10.1016/j.amjcard.2005.07.006
Wikipedia. Mean corpuscular volume. en.wikipedia.org
NHS. Vitamin B12 or folate deficiency anaemia: diagnosis. nhs.uk
National Institute for Health and Care Excellence (2024). Vitamin B12 deficiency in over 16s: diagnosis and management (NG239). nice.org.uk
NHS. Metformin. nhs.uk
NHS. Omeprazole. nhs.uk
NHS. B vitamins and folic acid. nhs.uk
NHS. Bowel cancer: symptoms. nhs.uk
NHS. Cough. nhs.uk
NHS. Mouth ulcers. nhs.uk