On this page
Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Yes, for assessment and arranging tests; treatment follows the results.
- Most nutrition and metabolism disorders are identified through blood tests; an online doctor can assess your symptoms, arrange the right tests, and start or refer treatment depending on what they show.
- An underactive thyroid causes fatigue, weight gain and feeling cold; an overactive one causes weight loss and a racing heart.
- Very high blood sugar with drowsiness, deep or rapid breathing or fruity-smelling breath is an emergency: call 112.
- Iron, B12, vitamin D and thyroid problems are the most common findings, and all are very treatable.
Some metabolic problems can become urgent. Call 112 or attend emergency care if you have very high blood sugar with drowsiness, deep or rapid breathing, fruity-smelling breath or confusion, or signs of very low blood sugar (shaking, sweating, confusion or collapse) that does not respond to sugar. Rapid unexplained weight loss, fainting, a racing or irregular heartbeat, or severe muscle weakness need prompt in-person assessment rather than an online consultation.
Can an online doctor help with nutrition and metabolism disorders?
Yes, as a first assessment and a route to the right tests, rather than as a place that treats every metabolic disease online. A licensed doctor can review symptoms such as tiredness, weight change or excessive thirst, decide which blood tests are needed (thyroid, glucose, iron, vitamin B12, folate, vitamin D and others), and then either start treatment or refer you.[1] Complex or rare metabolic diseases need specialist care.
This is deliberately an assess-and-refer page rather than a cure-all promise. The umbrella covers everything from a simple iron deficiency to inherited metabolic conditions, and no honest online service treats all of that by video. What it can do reliably is sort your symptoms, order the tests that answer the question, and get you onto the correct pathway quickly.
How an online consultation helps
tiredness, weight change, feeling cold, thirst or low mood have many causes, and the doctor sorts which point towards a nutritional or metabolic problem worth testing.[2]
rather than a scattergun panel, the doctor selects the tests your story actually calls for and explains what each one is checking.
confirmed deficiencies and common problems such as an underactive thyroid can often be started or managed after the results are back, with a clear review plan.[2]
where the picture points to specialist territory (complex diabetes, endocrine disease, or a rare metabolic disorder), the doctor says so and directs you, rather than stretching an online consultation past its limits.
What the doctor checks in an online nutrition and metabolism consultation
Because this is an umbrella of conditions, the consultation is a structured sorting exercise. The doctor will typically establish:
- Your main symptoms and their timeline: fatigue, weight gain or loss, thirst and urination, temperature intolerance, hair or skin changes, mood, and how quickly they have developed.
- Diet and absorption: your eating pattern, any restrictive or vegan diet, alcohol intake, and gut conditions or surgery that affect how you absorb nutrients, since deficiencies often start there.[1]
- Risk factors: family history of diabetes, thyroid or metabolic disease, pregnancy, age, and medicines that affect metabolism or nutrient levels.
- Thyroid and endocrine clues: features suggesting an underactive or overactive thyroid, and other hormonal patterns worth testing.[2]
- Blood-sugar signals: excessive thirst, frequent urination, unexplained weight loss and fatigue, which together raise the question of diabetes and prompt glucose testing.[3]
- Red and amber flags: rapid weight loss, fainting, palpitations, or symptoms of a metabolic emergency that move you straight to in-person care.
- What has been tested before: recent blood results, so the plan builds on them rather than repeating them.
What counts as a nutrition or metabolism disorder?
It is a broad family of conditions in which the body's supply of nutrients or its handling of energy goes wrong. Grouping them helps show where an online doctor fits.
Nutritional deficiencies
Shortfalls of iron, vitamin B12, folate or vitamin D are among the most common and the most treatable. They cause tiredness, breathlessness, pins and needles, mouth or tongue changes, or bone and muscle aches, and they are confirmed on a blood test and corrected with diet or supplements.[1][4] Poor absorption, for example from coeliac disease or after gut surgery, is a frequent hidden cause, which is why the doctor asks about your digestion.
Thyroid and other endocrine problems
The thyroid sets your metabolic pace. An underactive thyroid causes fatigue, weight gain, feeling cold and low mood; an overactive one causes weight loss, a racing heart, heat intolerance and anxiety. Both are diagnosed on thyroid blood tests, and an underactive thyroid in particular is commonly managed in general practice once confirmed.[2]
Diabetes and blood-sugar disorders
Diabetes is the metabolic disorder people know best. The warning signals (increased thirst, passing more urine, unexplained weight loss, tiredness and blurred vision) deserve prompt testing, because early diagnosis changes the outlook. Type 2 diabetes is often identified and managed in primary care, while type 1 and complex cases need specialist input.[3] Rarer inherited conditions of metabolism (such as those affecting how the body handles specific sugars, fats or minerals) sit firmly in specialist care.
Why blood tests are central
Almost every condition in this group is confirmed or excluded by a blood test, not by examination alone, which shapes how the online pathway works. The doctor's job in the consultation is to decide which tests your symptoms justify, arrange them, and interpret the results with you, rather than to guess a diagnosis from the outside. Where you have the blood drawn varies by country, and your doctor confirms the local route. Once results are back, some conditions can be treated or started straight away, while others define a clear referral. Being upfront about that sequence is the whole point of an assess-and-refer page: the value is an accurate first step and the right test, not a promise to fix everything by video.
What can be handled online, and what is referred?
This is the heart of the page. This is the framework our doctors use to decide, aligned with the cited guidance.
Swipe sideways to compare →
| Presentation | Likely first step | Suitable for online care? | When referral or in-person care is needed |
|---|---|---|---|
| Tiredness or symptoms suggesting a common deficiency (iron, B12, folate, vitamin D) | Targeted blood tests, then diet or supplement treatment[1] | Usually yes | Severe deficiency, no response, or an underlying cause needing investigation |
| Symptoms of an underactive thyroid | Thyroid blood tests; start or manage treatment once confirmed[2] | Often yes | Overactive thyroid, pregnancy, or an uncertain or complex result |
| Blood-sugar warning signs (thirst, urination, weight loss) | Glucose testing; assessment for type 2 diabetes[3] | Assessment and often ongoing care | Suspected type 1, very high readings, or complications |
| Suspected rare or inherited metabolic disorder | Assessment and specialist referral | Assessment and referral only | Always: these are managed in specialist metabolic services |
| Metabolic emergency (very high or low blood sugar, collapse) | Emergency care | No | Call 112 or attend urgently |
Availability of individual medicines and who may prescribe them vary by country; your doctor confirms what applies where you are.
Not sure which row is you? A doctor can tell you in one consultation. €47, exact price shown before payment.
See available times →Treatment options for nutrition and metabolism disorders
What you can do yourself
A varied diet covers most nutritional bases: iron from red meat, pulses and leafy greens; B12 from animal foods, with fortified foods or supplements important for vegans; vitamin D from sunlight and oily fish, with supplements often sensible in the darker European months.[1][5] Moderating alcohol and keeping active support metabolic health broadly. The honest caveat is this: self-diagnosing a deficiency and buying high-dose supplements online is a poor substitute for a blood test, because the symptoms overlap heavily and some supplements can cause harm in excess. Bring your symptoms to the consultation rather than a self-prescribed cupboard of tablets.
Treatment after your results
A prescription is never issued without a consultation, and in this group it usually follows the blood results rather than the call. Confirmed iron, B12, folate or vitamin D deficiency is corrected with the right dose and form, then rechecked; a confirmed underactive thyroid is treated with thyroid hormone replacement and monitored;[2] and type 2 diabetes is managed with lifestyle change and, where needed, medicines, with ongoing review.[3] Where results point to an overactive thyroid, suspected type 1 diabetes, a complex endocrine problem or a rare metabolic disease, the treatment is specialist, and the doctor arranges referral rather than starting something unsuitable online. Prescribing pathways vary by country, and your doctor confirms what applies to you.
When it might be something else
Tiredness and weight change are famously non-specific, and part of the consultation is keeping the wider picture in view. Persistent digestive symptoms with deficiency can signal malabsorption, which links to conditions such as coeliac disease and is why the doctor may ask about your gut and consider our diarrhoea and constipation assessments. B12 deficiency from an autoimmune stomach condition connects to gastritis. Fatigue can equally reflect poor sleep, low mood, anaemia or a chronic illness, and thirst and weight loss can have causes beyond diabetes. Testing is what separates these, which is why the plan centres on the right bloods rather than a snap label.
When we assess online, and when we refer you
We assess and often treat online: common nutritional deficiencies confirmed on testing; a confirmed underactive thyroid; assessment of blood-sugar warning signs and ongoing type 2 diabetes care; and interpreting recent results to plan sensible next steps. These are the parts of this umbrella an online GP can plausibly act on, and they cover most people who search for help here. Nutrition and metabolism concerns sit alongside our wider stomach and digestive problems assessments.
We refer or redirect you: an overactive thyroid, suspected type 1 diabetes, complex or poorly controlled diabetes, other endocrine disease, and any suspected rare or inherited metabolic disorder are directed to specialist services, because that is where they are properly managed. Anything suggesting a metabolic emergency is exactly that. In those cases the consultation gives you a fast, accurate assessment and the correct referral, with a full refund if we cannot help online.
When to get in-person care
Call 112 or attend emergency care immediately if you have very high blood sugar with drowsiness, deep or rapid breathing, fruity-smelling breath or confusion; signs of very low blood sugar that does not respond to sugar; or collapse and severe weakness. Arrange urgent in-person assessment for rapid unexplained weight loss, fainting, a persistently racing or irregular heartbeat, or severe muscle weakness. These need timely examination and tests that an online consultation cannot substitute for.
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Listen · 23 Feb 2026 →How Mobi Doctor works
- Book a time that suits you: open daily 7am–11pm, often the same day, with the exact price, €47, shown before you pay.
- Speak to a licensed doctor about nutrition and metabolism disorders: a private video consultation, from anywhere in Europe.
- Get your test plan and next steps: treatment or referral follows once results are back, and a prescription is never issued without a consultation. If we can’t help you online, you get a full refund.
Frequently asked questions about nutrition and metabolism disorders
Can an online doctor order blood tests in the EU?
The doctor can advise which blood tests you need and direct you to have them done; where you get them varies by country, and your doctor confirms the local route. Once results are back, they interpret them with you and either start treatment or refer you. A prescription is never issued without a consultation.
How much does a consultation cost?
A video consultation costs €47. The exact price is shown before payment, and there is no subscription. If the doctor can’t treat you online, you get a full refund and clear directions to the right care.
Can you diagnose a vitamin deficiency online?
Not from symptoms alone. Deficiencies of iron, B12, folate or vitamin D are confirmed on a blood test, because their symptoms overlap heavily with each other and with other conditions. The doctor arranges the right tests and treats a confirmed deficiency with the correct dose, then rechecks.
Can an online doctor help with thyroid or diabetes?
Yes, for much of it. A confirmed underactive thyroid and type 2 diabetes are commonly assessed and managed in primary care, which an online doctor can do with the right tests and reviews. An overactive thyroid, suspected type 1 diabetes and complex cases are referred to specialists.
Should I just buy supplements instead?
Not before you know what, if anything, is low. Self-prescribed high-dose supplements can be wasteful and occasionally harmful, and they can mask the real cause of your symptoms. A short consultation and the right blood test is a far more reliable route than guessing.
Why is this filed under stomach and digestive problems?
Many nutritional problems begin in the gut, through how well you absorb nutrients, so there is a genuine overlap. If your symptoms point clearly to a thyroid, blood-sugar or other cause, the doctor focuses there and refers on where specialist care is the right answer.
How quickly can I speak to a doctor?
Appointments are available daily from 7am to 11pm, often the same day. You choose a slot that suits you, and the doctor reviews your symptoms and any previous results during the call.
- Malnutrition: fact sheet, WHO, World Health Organization, 2024.
- Hypothyroidism: Clinical Knowledge Summary, NICE, National Institute for Health and Care Excellence, 2024.
- Type 2 diabetes in adults: management (NG28), NICE, National Institute for Health and Care Excellence, 2015 (updated 2022).
- Anaemia fact sheet, WHO, World Health Organization, 2025.
- Vitamin D, HSE, Health Service Executive (Ireland), accessed August 2026.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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Listen · 23 Feb 2026 →Speak to a doctor about nutrition and metabolism disorders today
Licensed doctors · open daily 7am–11pm · €54, exact price before payment
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