Black or tarry stools, stools with visible blood, vomiting blood or material that looks like coffee grounds, and sudden severe belly pain need emergency care. Call 911 or your local emergency number now.
The classic description is a burning or gnawing ache in the upper middle of the abdomen, somewhere between the breastbone and the navel. It can last minutes or hours, and it often comes and goes over weeks rather than running steadily. Research suggests that a meaningful share of peptic ulcers produce no symptoms at all until a complication appears 1.
Other common complaints include fullness after a small meal, bloating, belching, nausea, loss of appetite and pain that wakes you during the night. These complaints overlap heavily with reflux, indigestion and several other upper gut problems, so symptoms alone cannot identify an ulcer 2.
Most stomach ulcers trace back to two causes, infection with Helicobacter pylori and the use of some medicines. Research suggests that these two account for the large majority of peptic ulcers 3. H. pylori is a bacterium that can live in the stomach lining for years quietly, and studies indicate that clearing it substantially reduces the chance an ulcer returns 1.
The second cause is easier to describe than to judge on your own. Some medicines can irritate the stomach lining or weaken its defences, and the combination of several of them raises the stakes further. Do not stop anything you take on your own. Ask your prescriber whether anything on your list could be playing a part, because that is a decision for the person who prescribed it.
Everyday habits sit in the background rather than at the centre. Smoking is associated with peptic ulcer disease and with a higher chance of complications, and heavy alcohol use irritates the stomach lining 4. Short sleep, high stress and a heavy training block can make upper belly pain feel louder and can push people toward late meals, more alcohol and more over-the-counter remedies. None of those habits shows up as a lab finding, which is part of why a blood panel is a supporting tool here rather than the answer.
Life stage matters too. Family history, prior ulcers and a history of H. pylori infection all raise a clinician's suspicion when upper belly pain shows up again.
It is worth being blunt about one thing. Spicy food, coffee and acidic meals can aggravate an existing sore and make the burn worse for an hour, but they are not the reason the sore formed.
No blood test can confirm or rule out a stomach ulcer, but a few markers help a clinician judge whether an ulcer is bleeding and how much blood has been lost. Ulcers are seen directly at endoscopy, and H. pylori is checked with its own dedicated tests 2. Blood work earns its place by catching quiet blood loss and by tracking how the body is coping.
| Marker | Why it is linked to this symptom | What a result can and cannot tell you |
|---|---|---|
| Hemoglobin | Measures the oxygen-carrying protein in red blood cells, and slow bleeding from an ulcer drains it over weeks or months | A low value can flag blood loss or anemia from another cause. It cannot locate the source, it cannot confirm an ulcer, and it can still look normal in the first hours of a fast bleed |
| BUN | Blood urea nitrogen climbs when blood inside the gut is digested and absorbed as protein, and when reduced blood volume lowers flow through the kidneys | A rise alongside a steady creatinine can support suspicion of bleeding higher up in the gut. It also moves with dehydration, protein intake and kidney function, so it is never read alone |
| Ferritin | Reflects stored iron, and repeated small blood losses empty those stores before hemoglobin starts to fall | A low value points to depleted iron and prompts a search for where the iron is going. Ferritin rises with inflammation, so a normal value does not rule out ongoing loss |
Typical lab reference ranges give you a frame for your own report.
| Marker | Typical lab reference range |
|---|---|
| Hemoglobin (adult men) | roughly 13.5 to 17.5 g/dL |
| Hemoglobin (adult women) | roughly 11.5 to 16 g/dL |
| BUN (adults) | roughly 7 to 20 mg/dL |
| Ferritin | varies widely by lab, sex and assay |
These are typical lab reference ranges, not targets. Ranges vary by lab, age and sex, so read your own values against the range printed on your report.
Yes, a falling Hemoglobin is one of the clearest signals that an ulcer has been bleeding, although it is not specific to the stomach. Hemoglobin is the protein inside red blood cells that carries oxygen. When an ulcer erodes into a small vessel, blood is lost slowly into the gut, iron stores drain first, and hemoglobin falls later. The result can be fatigue out of proportion to your week, breathlessness on stairs that used to be easy, lightheadedness, pale skin and a resting heart rate that has crept up.
Bleeding is the most common complication of peptic ulcer disease, and studies indicate that the degree of blood loss shapes how urgently endoscopy is arranged 6. Hemoglobin also guides the resuscitation decisions a clinician makes in an acute bleed, and it is tracked repeatedly rather than read once 7.
Timing matters. In the first hours of a brisk bleed, hemoglobin can look deceptively normal because plasma and red cells are lost together, and the number only drops once fluid shifts back into the circulation. That is one reason a single reassuring value never cancels out a worrying symptom.
Plenty of other things move hemoglobin. Dehydration concentrates the blood and nudges it up. Heavy menstrual bleeding, pregnancy, altitude, endurance training, kidney function, B12 or folate status and chronic inflammation all shift it in one direction or another. A low hemoglobin is a reason to ask where the iron or the blood is going, not an answer in itself, and it is worth discussing with a clinician promptly.
BUN often rises during bleeding in the upper gut because blood that is digested in the small intestine is absorbed as protein and converted into urea by the liver. A second reason stacks on top. Blood loss lowers circulating volume, the kidneys receive less flow, and urea clearance drops. The result is a BUN that climbs while creatinine stays roughly where it was, a pattern a clinician reads as a hint rather than a verdict.
That pattern is useful enough that blood urea sits inside the scoring tools clinicians use to triage people with suspected bleeding from a peptic ulcer, alongside hemoglobin and blood pressure 7. Those scores help decide who needs urgent assessment and who can be assessed less urgently, and they are applied by clinicians, not by patients reading a report at home.
BUN is also one of the easiest markers to misread in isolation. It rises with dehydration, with a very high protein intake, with reduced kidney function and during catabolic states such as illness or injury. It falls with low protein intake, with liver disease and in pregnancy. Muscle mass and age shift it too. This is exactly why BUN is interpreted next to creatinine, electrolytes and a full blood count rather than on its own.
A completely normal blood panel does not rule out a stomach ulcer. An ulcer that is not bleeding, or that bleeds so slowly that iron stores still cover the loss, leaves no fingerprint on routine blood work at all. Endoscopy is how ulcers are seen and graded, and biopsies taken during that procedure also answer other questions a blood test cannot 2.
H. pylori is a separate question with separate tests. Breath testing, stool antigen testing and tests on tissue taken at endoscopy are the standard ways the infection is checked, and guidelines set out when each is used 8. A routine panel does not include any of them.
Blood work also cannot sort out the overlap. Upper belly burning can come from reflux, from the gallbladder, from the pancreas, from functional indigestion or from the heart, and the symptom descriptions blur into one another 2. That overlap is the whole reason clinical assessment comes first and labs come second.
Finally, blood work says nothing about the habits that shape how you feel day to day. Sleep debt, alcohol, late meals, training load and stress all change how upper belly pain registers, and none of them appears on a report. The honest summary is that labs narrow the field and flag bleeding. They do not see the sore.
Get emergency care now for vomiting blood or material that looks like coffee grounds, for black tarry stools or visible blood in the stool, for sudden severe belly pain, or for fainting, confusion or a racing heart alongside belly pain. Sudden, severe, unrelenting upper abdominal pain can signal a perforated ulcer, which is a surgical emergency 9. Bleeding and perforation are the two complications that turn an ulcer from a slow problem into an immediate one 5.
Arrange a prompt appointment, rather than an emergency visit, for upper belly pain that has lasted more than a couple of weeks, pain that keeps waking you at night, persistent vomiting, difficulty swallowing, unintended weight loss, new fatigue or breathlessness, or a known low hemoglobin that has not been explained. New upper belly symptoms in an older adult deserve earlier assessment rather than watchful waiting.
If you take medicines regularly and you are worried about your stomach, raise it with your prescriber rather than stopping anything yourself. Never ignore an abnormal lab result, and never read one value as a diagnosis.
If you are having thoughts of self-harm, call or text 988 (US) or your local emergency number now.
Hemoglobin and BUN are both measured on a standard blood draw, and the FitScript Essential panel includes them alongside the rest of a baseline metabolic and blood count picture. A draw takes a few minutes, and the markers are read together rather than one at a time.
Once results land, Atlas, FitScript's AI health advisor, explains what each value means in plain language, which values sit outside the typical range, and what a pattern across several markers can and cannot suggest. Members retest across the year, with 150+ biomarkers tested per year, so a hemoglobin that has drifted down over two draws is visible as a trend rather than as a single snapshot.
Atlas does not diagnose and does not decide on care. A licensed clinician reviews the picture, decides whether endoscopy, H. pylori testing or anything else is appropriate, and any management decisions belong to a licensed provider.
This page is educational and is not medical advice. Discuss your symptoms, your results and any next step with a clinician or licensed provider.
Related reading, burning stomach causes covers the other reasons an upper belly burn shows up, and heartburn vs heart attack explains how chest and upper belly symptoms are told apart.
The most common sign is a burning or gnawing ache in the upper middle of the abdomen. Fullness after small meals, bloating, belching, nausea, loss of appetite and pain that wakes you at night often come with it. These signs overlap with several other conditions, so a clinician decides what is behind them.
Most people describe a dull burn or a hunger-like gnawing between the breastbone and the navel. It can last minutes or hours and tends to come and goes over weeks rather than staying constant. Eating may ease it or set it off. Sudden severe pain is different and needs emergency care.
They can feel different, though not reliably enough to tell them apart at home. Pain from an ulcer in the duodenum, the first part of the small intestine, often eases shortly after eating and returns a few hours later or at night. Pain from a gastric ulcer is more often triggered by eating.
Two causes sit at the top of the list, infection with the bacterium Helicobacter pylori and the use of some medicines. Smoking and heavy alcohol use add to the risk. Ask your prescriber whether anything you take could irritate your stomach lining, and do not stop any medicine on your own.
No blood test can confirm or rule out an ulcer. Hemoglobin, BUN and ferritin help a clinician judge whether an ulcer may be bleeding and how much blood has been lost over time. An ulcer itself is seen during endoscopy, and H. pylori is checked with its own separate tests.
Everyday stress does not sit at the top of the list of causes. A stomach bacterium and some medicines explain most ulcers, which is why your prescriber is the right person to ask about your medicine list. Stress, short sleep and alcohol can still make existing upper belly pain feel worse.
A clinician confirms an ulcer by looking at the lining directly during an upper endoscopy, sometimes with small tissue samples taken at the same time. H. pylori is checked separately with a breath test, a stool test or a tissue sample. Blood work supports the picture but does not confirm it.
Call 911 or your local emergency number for vomiting blood or coffee-ground material, black tarry stools, visible blood in the stool, or sudden severe belly pain. Fainting, confusion or a racing heart alongside belly pain also needs emergency care. Do not wait to see whether the symptoms settle on their own.