Diabetes Insipidus

last authored: October 2009, David LaPierre

 

Introduction

Diabetes insipidus (DI) results from an inability of the kidneys to concentrate urine.

 

 

 

The Case of...

a simple case introducing clincial presentation and calling for a differential diagnosis. To get students thinking.

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Causes and Risk Factors

Central DI results from decreased ADH production in the brain. Causes include:

Nephrogenic DI results from:

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Pathophysiology

Central DI is caused by a loss of ADH-secreting cells from the posterior pituitary.

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Signs and Symptoms

  • history
  • physical exam

History

Central DI presents with polyuria, polydipsia, and enuresis

Nephrogenic DI leads to polyuria, failure to thrive, vomiting, and dehydration leading to hypernatremia.

Physical Exam

 

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Investigations

  • lab investigations
  • diagnostic imaging

Lab Investigations

Fasting serum osmolality above 650 excludes DI, and if 24-h urine volume is below 2.5L and serum Na is normal, DI is unlikely.

 

Urinalysis shows a dilute urine (SG <1.010) and low urine osmolality.

Increased serum osmolality and hypernatremia are also present.

ADH administration test leading to >50% change in urine osmolality suggests central cause.

Diagnostic Imaging

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Differential Diagnosis

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Treatments

Central DI is managed with DDAVP, given intranasally, SC, or PO.

Nephrogenic DI is managed with a low solute diet or with thiazide diuretics (????)

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Consequences and Course

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Additional Resources

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Topic Development

created:

authors:

editors:

reviewers:

 

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