Understanding Lab Tests for Overhydration
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Overhydration, also known as water intoxication or hyponatremia, occurs when the body takes in more water than it can eliminate, leading to an imbalance in electrolytes and blood chemistry. There is no single blood test that directly diagnoses overhydration, but laboratory testing is fundamental for assessing the body's response and monitoring potential complications.
Top Recommended Test
Urea Nitrogen (BUN)
This blood test measures urea nitrogen levels, which can become diluted during overhydration. When someone drinks too much water, BUN levels typically decrease as the blood becomes more diluted, helping healthcare providers assess the severity of water overload.
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Why Lab Testing is Important for Overhydration
Overhydration can dilute blood components and affect kidney function, leading to potentially dangerous electrolyte imbalances. Lab tests help healthcare providers assess these internal changes, monitor the dilution effects on blood chemistry, and evaluate how well the kidneys are concentrating urine.
Other Relevant Tests
Benzene Incident, Urine (OSHA)
This urine test can reveal low specific gravity levels, which may indicate overhydration or kidney dysfunction. When the body is overhydrated, the kidneys may not properly concentrate urine, resulting in diluted urine that can be detected through specific gravity measurements.
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Understanding the Results
These tests work together to provide a comprehensive picture of how overhydration is affecting the body's fluid balance and kidney function. Abnormal results may indicate the need for immediate medical intervention to restore proper electrolyte balance and prevent serious complications.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment. Severe overhydration can be a medical emergency requiring immediate attention.
