Standard of Care: Bile Acid Replacement Therapy

Because CBAS1 (HSD3B7 deficiency) is caused by a specific missing enzyme, it has a targeted treatment. This therapy does not just manage symptoms; it addresses the core biological failure of the disease ^[1]. For many children, this treatment allows the liver to function more normally and supports healthy growth and development ^[2].

The Standard of Care: Cholic Acid Therapy

The primary treatment for CBAS1 is oral cholic acid (brand name Cholbam). Cholic acid is a “primary” bile acid—the kind your child’s liver cannot make on its own ^[3].

This medication works in two vital ways:

1. Suppression: It sends a signal to the liver to “stop” trying to make bile acids. This prevents the buildup of the toxic, abnormal intermediates that cause liver damage ^[4][5].
2. Replacement: It provides the bile acids necessary to absorb fats and fat-soluble vitamins from food, which are essential for brain development, bone health, and proper blood clotting ^[6][7].

Dosing and Administration

Your child’s medical team will prescribe the dose based on their weight and the specific product label. In clinical studies, a common starting range is 10 to 15 mg/kg of body weight per day ^[5][8].

Important Administration Guidelines:

• Always take cholic acid strictly as directed by your specialist. Do not adjust the dose independently.
• It is generally administered with food.
• Ask your pharmacist exactly how to handle capsules or granules for an infant (e.g., whether they can be opened or mixed, and what not to crush or chew).
• Ask your team for written instructions on what to do if a dose is vomited or missed, and do not compensate for a missed dose unless instructed.
• Certain other medications (like bile-acid-binding resins or antacids) can interfere with absorption; review all medications with your pharmacist.

Monitoring and Vitamin Support

Because of malabsorption, your child will likely need extra help getting nutrients.

• Individualized Vitamin Supplementation: Your specialist will prescribe specific, often water-miscible, formulations of vitamins A, D, E, and K ^[6][8]. Do not start, stop, or change doses of over-the-counter supplements yourself. Fat-soluble vitamins can accumulate and cause toxicity (especially A and D).
• Ongoing Checks: Your specialist will regularly check blood levels of these vitamins and monitor PT/INR (a clotting test used to assess Vitamin K status) ^[8][9]. Improved bile-acid absorption does not guarantee that supplementation can be stopped.

Potential Side Effects and Precautions

While many children tolerate cholic acid well over long periods, it requires careful oversight ^[1]:

• Gastrointestinal Issues: Some children may experience diarrhea, nausea, or stomach pain ^[6].
• Advanced Liver Disease: If a child already has significant liver scarring (cirrhosis), doctors must use extreme caution. In advanced disease, cholic acid can sometimes cause liver markers to rise, indicating liver stress ^[10].
• Mandatory Lab Work: It is vital to never skip scheduled blood tests. Worsening bilirubin or transaminases may require prompt specialist assessment and holding or discontinuing treatment under the prescribing information ^[10][8].

With consistent treatment and monitoring, many children with CBAS1 lead healthy, active lives, potentially avoiding the need for a liver transplant ^[1][11].