LPAC stands for low phospholipid-associated cholelithiasis, a genetic condition that causes gallstones to form in both the gallbladder and the bile ducts inside the liver. It accounts for roughly 1% of all patients admitted to hospitals for symptomatic gallstones, but it’s disproportionately common in younger adults. The median age at first symptoms is 27, and about 77% of diagnosed patients are female.
What makes LPAC different from ordinary gallstones isn’t just who gets it or when. The underlying problem, the way it’s treated, and what happens after surgery are all distinct. If you or someone you know has been told they have LPAC, understanding those differences matters.
How LPAC Differs From Ordinary Gallstones
With typical gallstone disease, the liver secretes too much cholesterol into bile. Risk factors include older age, higher body weight, and being female. LPAC works through a completely different mechanism: the liver doesn’t secrete enough phospholipids into bile. Phospholipids act like a detergent that keeps cholesterol dissolved. Without enough of them, cholesterol crystallizes and forms stones.
This distinction has real consequences. In ordinary gallstone disease, stones form in the gallbladder. In LPAC, stones form in the gallbladder and inside the bile ducts of the liver itself. That’s a critical difference because removing the gallbladder can’t address stones that are forming upstream, inside the liver. LPAC also tends to strike younger, leaner patients who don’t fit the classic gallstone profile.
The Genetic Cause
LPAC is caused by mutations in a gene called ABCB4. This gene provides instructions for making a protein that acts like a flipper on the surface of liver cells. It moves phospholipids from the inside of the cell membrane to the outside, then releases them into bile. When the gene is mutated, the protein can’t do its job properly, and bile ends up with dramatically reduced phospholipid levels while bile acid concentrations remain normal.
The result is bile that’s chemically unstable. Without phospholipids to keep cholesterol in solution, cholesterol precipitates out and forms microscopic crystals. Those crystals grow into small, pebble-like stones throughout the biliary system. Animal studies have confirmed that bile containing only trace amounts of phospholipids becomes supersaturated with cholesterol, consistent with this crystallization pattern. Because the condition is genetic, it runs in families and the underlying tendency to form stones never goes away on its own.
Symptoms and Who Gets It
The symptoms of LPAC look identical to regular gallstone attacks: episodes of sharp pain in the upper right abdomen, nausea, and sometimes jaundice. What sets LPAC apart is the pattern. Symptoms typically begin before age 40, and about 12% of patients experience their first episode before age 18 (the youngest reported case was 8 years old). Another 12% don’t develop symptoms until after 40, so age alone doesn’t rule it out.
A hallmark of the condition is that symptoms come back after gallbladder removal. In ordinary gallstone disease, surgery usually resolves the problem. In LPAC, the stones keep forming inside the liver’s bile ducts because the underlying phospholipid deficiency persists. This recurrence after surgery is often what finally prompts the correct diagnosis, though there’s typically a delay. In one large study, the median age at diagnosis was 36, roughly nine years after symptoms first appeared.
How LPAC Is Diagnosed
Doctors use a set of three clinical criteria established in 2003. Meeting two of the three is enough to confirm the diagnosis:
- Symptom onset before age 40
- Recurrence of biliary symptoms after gallbladder removal (once other causes like residual stones have been ruled out)
- Imaging evidence of stones inside the liver’s bile ducts (intrahepatic lithiasis)
Ultrasound is typically the first imaging tool used, and it can reveal echogenic foci, small bright spots inside the liver that indicate stones or crystals in the intrahepatic ducts. Genetic testing for ABCB4 mutations can support the diagnosis, though not every patient with clinically confirmed LPAC will have a detectable mutation on current sequencing panels.
Why Gallbladder Removal Isn’t Enough
This is the most important practical point about LPAC. Cholecystectomy (gallbladder removal) is the standard, usually definitive treatment for ordinary gallstones. For LPAC, it’s inadequate. The stones form because of a systemic problem with bile composition, not a gallbladder-specific issue. Removing the gallbladder addresses only the stones already sitting there while doing nothing about the ongoing crystallization happening throughout the biliary tree.
Case reports consistently show the same pattern: patients undergo gallbladder removal, feel better temporarily, then return months or years later with the same biliary pain, sometimes complicated by recurrent infections of the bile ducts (cholangitis) or even pancreatitis. Procedures like stenting the bile ducts can provide temporary relief, but durable remission typically requires medication.
Treatment With Bile Acid Therapy
The primary treatment for LPAC is a medication called ursodeoxycholic acid, often abbreviated UDCA. It’s a naturally occurring bile acid that works by improving the cholesterol-dissolving capacity of bile, compensating for the missing phospholipids. The typical starting dose is weight-based, around 10 mg per kilogram of body weight per day, and can be increased up to 20 mg/kg daily if symptoms persist.
UDCA is a long-term therapy. Because the genetic defect doesn’t change, most patients need to stay on it indefinitely to prevent new stone formation. Clinical evidence suggests the medication begins reducing episodes of biliary pain within about three to four weeks of starting treatment. Side effects are generally mild, with diarrhea being the most common. If that occurs, the dose can be lowered temporarily and gradually increased as the body adjusts.
A randomized trial (the ULTRA Pain trial) is currently evaluating whether UDCA meaningfully reduces pain episodes and improves quality of life in post-cholecystectomy LPAC patients, which should provide stronger evidence for what clinicians have long observed in practice.
Long-Term Outlook
With consistent UDCA therapy, many LPAC patients achieve significant symptom control and avoid further complications. Without treatment, the ongoing formation of stones in the liver’s bile ducts can lead to repeated infections, blockages, and potentially progressive liver damage, though the exact risk of developing cirrhosis or liver cancer from LPAC specifically has not been well quantified yet.
The biggest challenge for most patients isn’t the treatment itself but getting diagnosed in the first place. Because LPAC is uncommon and its symptoms mimic ordinary gallstone disease, many patients go through one or more surgeries and years of recurring pain before the correct diagnosis is made. If you’re under 40, have had gallstones, and continue to have biliary pain after gallbladder removal, LPAC is worth discussing with a gastroenterologist or hepatologist familiar with the condition.