The goal of this pilot study is to evaluate the feasibility of administering niacinamide to patients with autosomal dominant polycystic kidney disease, to develop methods to assess the biological efficacy of niacinamide, and to perform a preliminary exploration of its clinical effect on kidney cyst growth and kidney function.

Niacinamide is a form of vitamin B3. Vitamin B3 is found in many foods including yeast, meat, fish, milk, eggs, green vegetables, beans, and cereal grains. Recent studies in mice have shown that niacinamide, at high doses, may slow kidney cyst growth from polycystic kidney disease (PKD).

By doing this study, the researchers will determine if a larger, long-term study to test whether niacinamide slows progression of PKD is justified.

Inclusion Criteria:

• Confirmed diagnosis of autosomal dominant polycystic kidney disease
• eGFR > 90ml/min/1.73m2 as determined from the serum creatinine by the CKD-EPI equation
• Ability to give informed consent in English

Exclusion Criteria:

• History of liver disease or abnormal liver function test
• Heavy alcohol intake
• Chronic diarrhea or malabsorption syndrome
• Thrombocytopenia
• Hypophosphatemia
• Pregnancy or lactation or plan to become pregnant during the study
• Treatment with anti-epileptic drugs
• Treatment with tolvaptan, current or within 2 months prior to screening
• Participation in another interventional trial currently or within 30 days prior to screening
• Partial or total nephrectomy or renal cyst reduction (including aspiration) done <1 year ago
• Cardiac pacemaker
• Presence of magnetic resonance-incompatible metallic clips (e.g. clipped cerebral aneurysm)
• Body weight >159 kg (350 lbs) or untreatable claustrophobia