---
title: "What blood tests check for excessive thirst?"
type: symptom
url: "https://www.test-well.com/symptoms/excessive-thirst"
symptom: Excessive thirst
aliases:
  - always thirsty blood test
  - dry mouth and thirst
  - polydipsia
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-05
lab_fee_usd: 6
---

# What blood tests check for 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. High calcium and certain kidney and pituitary conditions also drive thirst and are caught by the same panel.


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

- Thirst with vomiting, abdominal pain, deep rapid breathing, fruity breath or confusion — emergency care (possible diabetic ketoacidosis)
- Thirst with very high urine output (many liters a day) — see a clinician promptly

## Why these tests for excessive thirst?

Glucose spilling into urine pulls water out of the body and triggers thirst. Elevated calcium and impaired kidney concentrating ability do the same. Medications (diuretics, some psychiatric drugs), dry mouth from mouth breathing and simple under-hydration are the common non-lab explanations.

## Which conditions do these tests help evaluate?

- [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 |
| --- | --- | --- | --- | --- | --- |
| [Diabetes Screening Panel](https://www.test-well.com/tests/diabetes-screening-panel) | Panel (3 tests) | $59.99 | $65.99 | Yes | 2–5 business days |
| [Kidney Health Panel](https://www.test-well.com/tests/kidney-health-panel) | Panel (4 tests) | $64.99 | $70.99 | Yes | 2–4 business days |
| [Hemoglobin A1c](https://www.test-well.com/tests/hemoglobin-a1c) | Test | $21.99 | $27.99 | No | 2–4 business days |
| [Glucose, Fasting](https://www.test-well.com/tests/glucose-fasting) | Test | $24.99 | $30.99 | Yes | 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 |
| [Urinalysis, Complete](https://www.test-well.com/tests/urinalysis) | Test | $17.99 | $23.99 | No | 1–3 business days |

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

## Common questions

### Do I need to fast?

Only for fasting glucose (8–12 hours). A1c, the metabolic panel and urinalysis can be done any time, though a morning draw covers all of them in one visit.

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- [All symptoms](https://www.test-well.com/symptoms)
- [Browse by condition](https://www.test-well.com/conditions)

---

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

Canonical page: https://www.test-well.com/symptoms/excessive-thirst
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.