---
title: "Which blood tests help explain chronic constipation?"
type: symptom
url: "https://www.test-well.com/symptoms/constipation"
symptom: Constipation
aliases:
  - blood test for constipation
  - constipation lab work
  - constipation thyroid test
  - chronic constipation blood tests
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-07
lab_fee_usd: 6
---

# Which blood tests help explain chronic constipation?

> Chronic constipation is usually diet, fluid, activity or medication related, but blood tests catch the metabolic causes worth excluding: an underactive thyroid (TSH), high calcium and low potassium or magnesium (metabolic panel), diabetes (A1c), and celiac disease. Blood in the stool, unexplained weight loss or new constipation after 50 need a clinician first — those are colonoscopy questions, not lab questions.


## When should you see a clinician instead of ordering a test?

- Blood in the stool or black, tarry stools
- Unexplained weight loss, or new persistent constipation after age 50
- Severe abdominal pain, vomiting, or no bowel movement with a swollen abdomen — same-day care
- Pencil-thin stools for weeks, or a family history of colon cancer

## Why these tests for constipation?

Hypothyroidism slows the gut and is one of the most common treatable causes of new constipation; TSH is the single highest-yield test. A metabolic panel checks calcium (high calcium constipates), potassium, glucose and kidney function.

A1c screens for diabetes, which affects gut nerves over time. Celiac antibodies are worth checking when constipation alternates with bloating or diarrhea — celiac presents with constipation more often than people expect.

A CBC looks for anemia, which alongside constipation can be a clue to blood loss in the bowel and shifts the priority to a clinician visit.

## Which conditions do these tests help evaluate?

- [Thyroid Problems](https://www.test-well.com/conditions/thyroid-problems) — TSH, Free T4/T3 and antibodies to evaluate an under- or over-active thyroid.
- [Celiac Disease](https://www.test-well.com/conditions/celiac-disease) — Celiac antibody testing and the markers used to screen for gluten-related disease.
- [Diabetes & Blood Sugar](https://www.test-well.com/conditions/diabetes-screening) — A1c, fasting glucose and insulin to screen for prediabetes and diabetes.

## Which tests, and what do they cost?

| Test or panel | Type | Price | All-in (one item + $6 fee) | Fasting | Results |
| --- | --- | --- | --- | --- | --- |
| [Complete Thyroid Panel](https://www.test-well.com/tests/thyroid-complete-panel) | Panel (4 tests) | $109.99 | $115.99 | No | 3–7 business days |
| [Gut Health Panel](https://www.test-well.com/tests/gut-health-panel) | Panel (5 tests) | $129.99 | $135.99 | No | 3–7 business days |
| [General Wellness Panel](https://www.test-well.com/tests/general-wellness-panel) | Panel (4 tests) | $89.99 | $95.99 | Yes | 1–3 business days |
| [TSH (Thyroid Stimulating Hormone)](https://www.test-well.com/tests/tsh) | Test | $26.99 | $32.99 | No | 1–3 business days |
| [Comprehensive Metabolic Panel](https://www.test-well.com/tests/comprehensive-metabolic-panel) | Test | $22.99 | $28.99 | Yes | 1–3 business days |
| [Hemoglobin A1c](https://www.test-well.com/tests/hemoglobin-a1c) | Test | $21.99 | $27.99 | No | 2–4 business days |
| [Celiac Disease Panel](https://www.test-well.com/tests/celiac-disease-comprehensive) | Test | $124.99 | $130.99 | No | 3–7 business days |
| [CBC with Differential](https://www.test-well.com/tests/cbc-with-differential) | Test | $21.99 | $27.99 | No | 1–3 business days |
| [Magnesium](https://www.test-well.com/tests/magnesium) | Test | $19.99 | $25.99 | No | 2–4 business days |
| [Calcium](https://www.test-well.com/tests/calcium) | Test | $26.99 | $32.99 | No | 1–3 business days |

Prices are cash-pay; every order adds one $6.00 lab processing fee. Physician authorization included.

## Common questions

### Can constipation be a thyroid problem?

Yes — it is one of the classic symptoms of hypothyroidism, often alongside fatigue, weight gain and feeling cold. A TSH (with free T4) answers it in one draw.

### Which electrolyte problems cause constipation?

High calcium and low potassium are the main ones; low magnesium contributes. A comprehensive metabolic panel covers calcium and potassium; magnesium is a separate test.

### Should I test for celiac disease if I'm constipated?

If constipation comes with bloating, fatigue, iron deficiency or a family history, yes. Keep eating gluten before the test — antibodies fall on a gluten-free diet and the result can read falsely normal.

## Related

- [What blood tests should you get for fatigue?](https://www.test-well.com/symptoms/fatigue)
- [Which blood tests help explain brain fog?](https://www.test-well.com/symptoms/brain-fog)
- [What blood tests should you get for hair loss?](https://www.test-well.com/symptoms/hair-loss)
- [What blood tests check for causes of unexplained weight gain?](https://www.test-well.com/symptoms/weight-gain)
- [All symptoms](https://www.test-well.com/symptoms)
- [Browse by condition](https://www.test-well.com/conditions)

## Sources

- [NIDDK — Constipation: symptoms and causes](https://www.niddk.nih.gov/health-information/digestive-diseases/constipation/symptoms-causes)
- [American Thyroid Association — Hypothyroidism](https://www.thyroid.org/hypothyroidism/)
- [Celiac Disease Foundation — Symptoms](https://celiac.org/about-celiac-disease/symptoms-of-celiac-disease/)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-06. Review policy: https://www.test-well.com/editorial-policy

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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.