--- title: Blood tests by symptom type: index url: "https://www.test-well.com/symptoms" review_status: reviewed --- # Which blood tests should you get for your symptom? > One page per symptom: the common testable causes, the tests that look for them with cash-pay prices, and the situations where a clinician or emergency care is the right first step instead of a lab order. - [What blood tests should you get for fatigue?](https://www.test-well.com/symptoms/fatigue) — Persistent fatigue has a short list of common, testable causes: an underactive thyroid, low iron stores, vitamin B12 or D deficiency, and blood-sugar problems. - [Which blood tests help explain brain fog?](https://www.test-well.com/symptoms/brain-fog) — Brain fog — poor concentration, slow recall, mental fatigue — is commonly linked to thyroid dysfunction, vitamin B12 deficiency, low iron, blood-sugar swings and low vitamin D. - [What blood tests should you get for hair loss?](https://www.test-well.com/symptoms/hair-loss) — Diffuse hair shedding is often driven by something measurable: low iron stores (ferritin), thyroid dysfunction (TSH), hormone shifts (testosterone, DHEA-S, SHBG) and low vitamin D or zinc. - [What blood tests check for causes of unexplained weight gain?](https://www.test-well.com/symptoms/weight-gain) — When weight climbs without a change in eating or activity, the testable causes are an underactive thyroid, insulin resistance and cortisol excess. - [Which blood tests are used for unexplained weight loss?](https://www.test-well.com/symptoms/unexplained-weight-loss) — Losing weight without trying deserves a prompt, broad look: an overactive thyroid, diabetes, celiac disease and chronic inflammation are the common testable causes. - [Why am I always cold? Blood tests that check the common causes](https://www.test-well.com/symptoms/cold-intolerance) — Feeling cold when others are comfortable is a classic hypothyroid symptom and a common sign of anemia or low iron. - [What blood tests are used for joint pain?](https://www.test-well.com/symptoms/joint-pain) — Blood tests sort joint pain into inflammatory, autoimmune and metabolic causes. - [Can blood tests find a physical cause of anxiety?](https://www.test-well.com/symptoms/anxiety) — Sometimes. - [What blood tests are worth checking for insomnia?](https://www.test-well.com/symptoms/insomnia) — Sleep problems have a few measurable contributors: a disrupted cortisol rhythm, thyroid dysfunction, low ferritin (linked to restless legs) and low magnesium. - [Which blood tests check for causes of low libido?](https://www.test-well.com/symptoms/low-libido) — Low sex drive is often hormonal and often testable: total and free testosterone (in men and women), SHBG, estradiol, prolactin and thyroid function are the standard set. - [What blood tests are used for muscle weakness?](https://www.test-well.com/symptoms/muscle-weakness) — Muscle weakness with no obvious cause is checked with creatine kinase (muscle breakdown), a comprehensive metabolic panel (electrolytes, kidney and liver), magnesium, vitamin D, TSH and morning cortisol. - [Which lab tests help with chronic bloating?](https://www.test-well.com/symptoms/bloating) — Chronic bloating with diarrhea, fatigue or weight change deserves a celiac screen (tTG-IgA with total IgA), a CBC and iron studies for the malabsorption it can cause, and stool calprotectin when inflammatory bowel disease is a concern. - [What blood tests help explain dry skin, acne and rashes?](https://www.test-well.com/symptoms/skin-problems) — Persistent skin changes sometimes have a systemic cause blood tests can find: dry, coarse skin with hypothyroidism; adult acne with androgen excess or PCOS; itching with liver, kidney or iron problems; and slow healing with high blood sugar or low zinc. - [What blood tests check the causes of frequent urination?](https://www.test-well.com/symptoms/frequent-urination) — Frequent urination with thirst is a classic sign of high blood sugar, so hemoglobin A1c and fasting glucose come first, with a urinalysis to check for infection, glucose and protein and a metabolic panel for kidney function and calcium. - [Which blood tests are used for irregular periods?](https://www.test-well.com/symptoms/irregular-periods) — Irregular or missed periods are evaluated with the hormones that run the cycle — FSH, LH, estradiol and progesterone — plus prolactin, TSH and androgens (testosterone, DHEA-S), which cover the common disruptors: PCOS, thyroid disease, high prolactin and perimenopause. - [What blood tests are used for erectile dysfunction?](https://www.test-well.com/symptoms/erectile-dysfunction) — Erectile dysfunction is often the first sign of a vascular or metabolic problem, so the workup checks more than testosterone: total and free testosterone with SHBG, hemoglobin A1c and glucose, a lipid panel, TSH and prolactin. - [What blood tests check for causes of numbness and tingling?](https://www.test-well.com/symptoms/numbness-and-tingling) — Tingling in the hands or feet has two very common testable causes: vitamin B12 deficiency and diabetes-related nerve damage. - [Which blood tests are used for shortness of breath?](https://www.test-well.com/symptoms/shortness-of-breath) — Breathlessness on exertion that builds over weeks is checked for anemia (CBC, ferritin, iron studies), heart strain (NT-proBNP) and thyroid disease (TSH). - [What blood tests are used for easy bruising?](https://www.test-well.com/symptoms/easy-bruising) — Bruising more easily than usual is checked with a CBC (platelet count), prothrombin time/INR (clotting factors), a comprehensive metabolic panel (liver function, since the liver makes clotting factors), and vitamin C, whose deficiency weakens blood vessels. - [What blood tests check for causes of night sweats?](https://www.test-well.com/symptoms/night-sweats) — Night sweats are most often hormonal — perimenopause and menopause in women, low testosterone in men — or thyroid-related, and those are testable: FSH, LH, estradiol, TSH with Free T4, and a CBC. - [Can blood tests explain mood swings and irritability?](https://www.test-well.com/symptoms/mood-swings) — Sometimes. - [What blood tests are used for heart palpitations?](https://www.test-well.com/symptoms/heart-palpitations) — Palpitations that come and go are commonly linked to an overactive thyroid, anemia, and low potassium or magnesium — all checked with TSH and Free T4, a CBC, a metabolic panel and magnesium. - [Which blood tests check for causes of dizziness?](https://www.test-well.com/symptoms/dizziness) — Lightheadedness — especially on standing — is checked for anemia (CBC, ferritin), low or high blood sugar (glucose, A1c), dehydration and electrolyte problems (metabolic panel), thyroid disease (TSH) and vitamin B12 deficiency. - [What blood tests check for excessive thirst?](https://www.test-well.com/symptoms/excessive-thirst) — Constant thirst with frequent urination is the textbook presentation of high blood sugar, so hemoglobin A1c and fasting glucose lead, with a comprehensive metabolic panel for sodium, calcium and kidney function and a urinalysis. - [What blood tests are used for swollen ankles and legs?](https://www.test-well.com/symptoms/swollen-ankles) — Swelling in both legs is checked for the organ causes — kidney (creatinine, eGFR, urine protein), liver (albumin, liver enzymes), heart (NT-proBNP) and thyroid (TSH) — with a comprehensive metabolic panel, urinalysis, NT-proBNP and TSH. --- Canonical page: https://www.test-well.com/symptoms Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.