Feeling worn out after a hard week is normal. Feeling tired for weeks, even when you sleep, is different. When fatigue will not lift, a blood test for fatigue is often one of the first tools a provider uses to find a treatable cause. At Palm Urgent Care on S Magnolia Ave in El Cajon, walk-in patients can talk through their symptoms with a provider, who may order lab testing based on their history and exam.
This guide is organized by cause, so you can see which labs connect to which problems. If you keep asking yourself, "Why am I always tired?", start here.
Common Medical Causes of Ongoing Fatigue
MedlinePlus lists many conditions that can cause fatigue, including anemia, thyroid disorders, diabetes, sleep problems such as insomnia and sleep apnea, infections, heart failure, depression, grief and stress. Common medicines can also leave you drained, including antihistamines, blood pressure medicines, sleeping pills, steroids and diuretics.
Labs are only part of the picture. Expect questions about how long the tiredness has lasted, your sleep, your medicines, and other symptoms such as weight change, fever or heavy periods. Those answers guide which tests make sense.
CBC and Anemia: The First Blood Test for Fatigue
A complete blood count (CBC) is one of the most common labs ordered when someone feels run down. According to MedlinePlus, a CBC measures red blood cells, white blood cells, platelets, hemoglobin (the protein that carries oxygen), hematocrit and the average size of your red blood cells. Abnormal red blood cell results may be a sign of anemia, too little iron, dehydration or heart disease.
The National Heart, Lung, and Blood Institute (NHLBI) explains that anemia can make you feel tired or weak and may also cause shortness of breath, dizziness, headaches or an irregular heartbeat. The most common type is iron-deficiency anemia. NHLBI notes that heavy menstrual periods, bleeding during childbirth and some digestive conditions raise the risk, and that diagnosis typically involves a CBC along with blood iron and ferritin levels.
Searching for an "anemia blood test near me" or a "CBC blood test walk-in" option? A provider visit means the labs are chosen to fit your symptoms.
Thalassemia Trait in Middle Eastern and Mediterranean Families
Not every unusual CBC means iron deficiency. Thalassemia is an inherited blood disorder that affects how the body makes hemoglobin. NHLBI reports that it occurs most often among people of South Asian, Italian, Greek, Middle Eastern and African descent. MedlinePlus adds that alpha thalassemia is most common in people of Southeast Asian, Middle Eastern, Chinese and African descent, and beta thalassemia in people of Mediterranean origin.
That matters for many Iraqi, Chaldean, Syrian and other Middle Eastern families in El Cajon. Someone who inherits a changed hemoglobin gene from one parent and a normal gene from the other is a carrier, said to have thalassemia trait. Carriers often have no signs of illness or only mild anemia, and NHLBI notes that when symptoms are minor or absent, a provider may first suspect thalassemia from a routine blood test. Some adults learn they carry the trait only after a CBC done for another reason.
Thalassemia trait symptoms
MedlinePlus notes that people with the minor form have small red blood cells but no symptoms. When thalassemia does cause anemia, NHLBI lists feeling tired or weak, shortness of breath, paleness, dizziness or fainting, and headaches. If a CBC raises the question, your provider may order special hemoglobin tests, and genetic testing can pin down the exact type. Knowing whether a low result comes from low iron or an inherited trait shapes the next step.
Vitamin D, Thyroid and Blood Sugar Tests
Vitamin D deficiency test
A vitamin D deficiency test measures 25-hydroxy vitamin D, which MedlinePlus calls the most accurate way to see whether you have enough. Low levels may cause bone pain and muscle weakness or aches. Rarely exposing skin to sunlight, from staying indoors or covering up outside, raises the risk.
A study of 550 female migrants in Al Ain, United Arab Emirates, available through the National Library of Medicine, found vitamin D deficiency in about 87% of the Arab women tested. The authors pointed to limited sun exposure from clothing that covers most of the body, and across the study, low physical activity and obesity were also linked with deficiency. Sunshine alone does not guarantee healthy levels.
Thyroid (TSH)
An underactive thyroid can cause fatigue, weight gain and feeling very sensitive to cold. A TSH blood test checks thyroid-stimulating hormone, and a level that is too high or too low may be a sign of a thyroid problem. Because hypothyroidism develops slowly, MedlinePlus notes that many people do not notice symptoms for months or even years.
Blood sugar
The CDC lists fatigue among common diabetes symptoms, along with increased thirst and hunger, frequent urination and blurry vision. Prediabetes and type 2 diabetes, however, often cause no symptoms. Blood tests such as the A1C, which reflects average blood sugar over the past two to three months, and a fasting blood sugar test are used to check for both.
When Fatigue Needs Same-Day Attention
Most fatigue is not an emergency. Some symptoms are.
Call 911 or go to the nearest emergency room if tiredness comes with:
- Chest pain or discomfort that lasts more than a few minutes, or that goes away and comes back
- Shortness of breath, or feeling weak, light-headed or faint, sometimes with a cold sweat
- Pain or discomfort in the jaw, neck, back, arms or shoulders
- Confusion, dizziness or vision problems
- Little or no urination, or sudden swelling with weight gain
The first three are heart attack warning signs from the CDC, which also notes that women are more likely to have symptoms such as unusual or unexplained tiredness and nausea. The last two come from MedlinePlus, which lists them as reasons to contact a provider right away.
If fatigue comes with thoughts of harming yourself, call or text 988 to reach the 988 Suicide & Crisis Lifeline.
For unexplained tiredness when you are otherwise stable, especially with fever, weight loss or regular sweats, MedlinePlus advises seeing a provider. That is a good fit for a walk-in urgent care visit.
What to Do After Your Results
- Ask what each result means. Request a copy and a plain explanation of any flagged value.
- Share results with your primary care provider, especially if a value is borderline or needs a repeat test.
- If thalassemia trait is found, tell close relatives. NHLBI notes that people who do not know whether they carry a thalassemia gene can ask their provider for a blood test, and couples who know they are at risk may want to meet with a genetic counselor before having children.
- If everything is normal, keep the conversation going. A normal blood test for fatigue does not rule out sleep problems, stress, low mood or medicine side effects.
See our guide to lab testing at urgent care, or browse all Palm Urgent Care services.
Frequently Asked Questions
Which blood test for fatigue should I ask for?
There is no single test. Providers often start with a CBC for anemia, then may add TSH, A1C or fasting glucose, iron studies or vitamin D, depending on your symptoms.
Why am I always tired even when I get enough sleep?
Anemia, thyroid problems, diabetes, sleep apnea, depression, infections and medicines can all cause ongoing tiredness. A provider visit, often with a few blood tests, helps narrow it down.
What are the symptoms of thalassemia trait?
Many people with thalassemia trait have no symptoms. Some have mild anemia, which can cause tiredness or weakness. It is often first suspected on routine blood work.
Can I walk in for a CBC blood test in El Cajon?
Palm Urgent Care in El Cajon (Magnolia) welcomes walk-in patients. A provider can evaluate you and, if needed, order labs such as a CBC. Call ahead to confirm which tests are done on site. Check the location page for current hours.
If you have felt run down for weeks, stop by Palm Urgent Care at 436 S Magnolia Ave, Suite 101, in El Cajon. For busy working families across East County, a walk-in visit is often easier to fit into the day. Visit the El Cajon (Magnolia) location page for hours, directions and coverage details.
This article is for general information and is not a substitute for medical advice from a licensed clinician.