Total Cholesterol 138 mg/dL: Is That Low?

Is Total Cholesterol 138 mg/dL Low, Normal, or High?

Total cholesterol 138 mg/dL is considered low based on standard clinical reference ranges. Most health organizations, including the American Heart Association and the National Heart, Lung, and Blood Institute, define desirable total cholesterol as under 200 mg/dL. While being well below that threshold might sound like great news, a reading of 138 mg/dL is unusually low and may warrant a closer look. Your doctor will want to understand why your cholesterol is this low, especially if it has dropped significantly from previous readings. Low total cholesterol is not automatically a problem, but it is worth exploring the full picture behind the number.

A total cholesterol level of 138 mg/dL signals a notably low reading, falling below the typical healthy range and prompting further clinical assessment. While public health emphasis often centers on managing high cholesterol, a persistently low value like 138 mg/dL is equally significant and warrants investigation into potential underlying health issues. Such levels can indicate conditions like malabsorption disorders, where the body struggles to properly absorb dietary fats and essential nutrients, or an overactive thyroid (hyperthyroidism), which accelerates metabolism and the breakdown of lipids. Less commonly, severe liver disease affecting cholesterol production or significant nutritional deficiencies could also be contributing factors. To pinpoint the cause, your healthcare provider will likely recommend a repeat fasting lipid panel, alongside specific diagnostic tests such as thyroid function assays or markers for malabsorption, and a thorough review of your medication regimen and dietary habits. A crucial detail often overlooked is that cholesterol is vital not just for heart health, but also for cell membrane integrity, hormone synthesis, and vitamin D production. Therefore, maintaining levels within an optimal window is essential, and an apparently "good" low number could signal systemic imbalances or deficiencies that require specific attention.

Hidden Risk of Total Cholesterol 138 mg/dL

A total cholesterol of 138 mg/dL often gets overlooked because most conversations about cholesterol focus on high readings. But very low cholesterol carries its own set of concerns that are less commonly discussed. Research from the National Institutes of Health has explored links between very low cholesterol and certain health outcomes that deserve attention.

A total cholesterol level of 138 mg/dL, while seemingly low, can mask underlying issues that increase the risk of certain health complications. This low value may indicate impaired nutrient absorption, potentially affecting fat-soluble vitamins like A, D, E, and K, which are crucial for immune function, bone health, and antioxidant defense. Furthermore, very low cholesterol can be associated with an increased risk of hemorrhagic stroke, as cholesterol plays a role in the structural integrity of blood vessel walls. It may also signal underlying inflammation or chronic disease processes that require investigation, rather than solely reflecting cardiovascular risk in the traditional sense.

• Some studies have found associations between very low total cholesterol and increased risk of hemorrhagic stroke, though the connection is still being researched
• Cholesterol plays a critical role in hormone production, cell membrane structure, and vitamin D synthesis. Very low levels may affect these processes
• Low cholesterol can sometimes be a sign of an underlying condition such as hyperthyroidism, liver disease, malnutrition, or malabsorption issues
• Certain medications, chronic infections, or severe illness can push total cholesterol unusually low as a secondary effect
• Mental health research has explored potential links between very low cholesterol and mood changes, though findings remain mixed and no firm conclusions have been drawn

What Does a Total Cholesterol Level of 138 mg/dL Mean?

Total cholesterol is a combined measurement of several types of cholesterol and fats in your blood. The basic formula is: total cholesterol equals LDL cholesterol plus HDL cholesterol plus 20 percent of your triglycerides. So when you see a total cholesterol number, it reflects multiple components working together rather than a single type of fat.

A total cholesterol reading of 138 mg/dL is most plausibly linked to a combination of significant dietary changes and potential underlying physiological factors. This specific level often arises from a very low-fat diet, particularly one that is deficient in healthy fats and excessive in refined carbohydrates, which can suppress HDL production. Malabsorption issues, such as those seen in celiac disease or inflammatory bowel disease, can also lead to such low levels by hindering fat and cholesterol uptake. Additionally, certain medications, including specific statins or antifungal agents, or even hyperthyroidism where the body excessively metabolizes cholesterol, could contribute to this reading.

Your body needs cholesterol. It is not simply a harmful substance. Cholesterol is essential for building and maintaining cell walls, producing hormones like estrogen and testosterone, creating bile acids that help you digest food, and synthesizing vitamin D. Every cell in your body uses cholesterol as part of its structure.

At 138 mg/dL, your total cholesterol is significantly below the desirable range of 150 to 199 mg/dL. For some people, this is simply their natural baseline driven by genetics, diet, and lifestyle. For others, it could signal that something else is going on. Your doctor will want to look at each component of the lipid panel individually. For example, if your HDL (the protective cholesterol) is very low, even a low total number might not be as reassuring as it first appears.

It is also important to understand that cholesterol levels are just one factor in overall health. A reading of 138 mg/dL does not tell the full story on its own. Your doctor will interpret it alongside your other lab results, medical history, and lifestyle factors to form a complete assessment.

Lifestyle Changes for Total Cholesterol 138 mg/dL

If your total cholesterol is 138 mg/dL and your doctor has ruled out underlying conditions, the focus shifts to making sure your body is functioning well overall. Regular physical activity supports healthy cholesterol balance. The American Heart Association recommends at least 150 minutes of moderate-intensity aerobic exercise per week, such as brisk walking, swimming, or cycling. Exercise tends to raise HDL cholesterol, which is especially important when total cholesterol is on the low side.

If your total cholesterol is 138 mg/dL, the immediate next step is to schedule a follow-up appointment with your primary care physician to discuss further diagnostic testing. This should include a full lipid panel to assess HDL, LDL, and triglycerides individually, as well as liver function tests and potentially tests for inflammatory markers or thyroid function. Lifestyle modifications should focus on ensuring adequate intake of healthy fats from sources like avocados, nuts, and olive oil, while moderating refined carbohydrate consumption. Tracking your dietary intake meticulously for a week before your next appointment will provide valuable data.

Maintaining a healthy weight is another key factor. Being significantly underweight can contribute to low cholesterol levels. If weight loss has been unintentional, it is worth mentioning to your healthcare provider. Sustainable body weight management supports stable cholesterol production.

Sleep quality also plays a role in cholesterol regulation. Research suggests that chronic sleep deprivation can alter lipid metabolism. Aiming for seven to nine hours of quality sleep per night supports your body's natural processes, including cholesterol production and balance.

Stress management matters as well. Chronic stress affects your hormonal balance, and since cholesterol is a building block for hormones, prolonged stress may influence your lipid profile in subtle ways. Finding consistent ways to manage stress, whether through exercise, spending time in nature, or simply resting, contributes to overall cardiovascular and metabolic health.

Written by

Ernestas K.

Clinical research writer specializing in human health, biology, and preventive medicine.

Reviewed against AHA, NIH, ACC, Mayo Clinic, PubMed guidelines · Last reviewed March 20, 2026