Metformin and Congenital Nephrogenic Diabetes Insipidus

Study Overview
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Brief Summary
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The purpose of this study is to determine whether metformin can increase urine concentration (osmolality) and decrease the amount of urine in patients with congenital nephrogenic diabetes insipidus (NDI).

Detailed Description
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Nephrogenic diabetes insipidus (NDI) is a genetic disease. Patients with this disease make large amounts of urine because their kidneys don't hold on to water. The large amount of urine means that patients need to urinate very frequently. They are also at increased risk for dehydration if they don't drink enough. The large amount of urine can sometimes damage their bladders and kidneys. There are some medicines that may help these patients urinate less, but they are not very effective. There is evidence in animal studies that a medication called metformin may help patients with NDI urinate less.

Official Title
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Use of Metformin to Treat Patients With Congenital Nephrogenic Diabetes Insipidus (NDI)

Conditions
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Diabetes Insipidus

Intervention / Treatment
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* Drug: Metformin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males with a documented mutation in the vasopressin type 2 receptor (V2R) Willing to provide consent and/or assent as appropriate Capable of providing urine samples as dictated by the protocol Exclusion Criteria: Urinary incontinence Subjects who have heart disease, liver disease, diabetes, cancer, or other significant disease other than Nephrogenic Diabetes Insipidus (NDI) Subjects with significant renal dysfunction (defined as a calculated glomerular filtration rate (GFR) <80 ml/min/1.73 m^2) Subjects with acquired NDI

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Metformin<br>Subjects with congenital nephrogenic diabetes insipidus (NDI) will receive one metformin 500 mg pill orally | Drug: Metformin<br>* Metformin 500 mg pill dispensed once orally<br>* Other names: Riomet;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in mean urine osmolality | Urine osmolality is a measure of urine concentration. Urine osmolality will be measured using a Wescor vapor pressure osmometer. A normal range for urine osmolality is approximately 500-850 mOsm/kg water. Change is the difference in average osmolality from baseline to 7 hours. | Baseline, 7 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in mean urine volume | Urine volume is a measure of fluid balance. Change from baseline in average volume of urine collected from baseline to 7 hours. | Baseline, 7 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Congenital nephrogenic diabetes insipidus