Dear Doctor: I have been taking levothyroxine for an underactive thyroid for about 40 years. I have progressed from 0.025 milligrams to 100 milligrams currently. I recently read an article indicating that long-term use of this drug increases the incidence of bone fractures by about 80 percent. I am 74 years old. What alternatives are available to treat this condition?

Dear Reader: I can understand your worry about thyroid hormone and an increased risk of fractures, especially after being on the medication for 40 years. After all, people with hyperthyroidism (an excess of thyroid production) have a greater risk for osteoporosis, and studies have found that thyroid hormone increases bone resorption while interfering with calcium metabolism within the bone.

In fact, people with hyperthyroidism have a 10 to 20 percent decrease in bone density compared to people with normal thyroid levels; they also have an increased risk of fracture. A 2014 study from Denmark showed that, after 7.5 years, women with hyperthyroidism showed a fracture rate of 12.5 percent while those who had normal thyroid levels had a fracture rate of 7.6 percent. (This increased fracture rate was not seen in men.)

The impact of taking thyroid hormone to keep your levels normal is less clear. So far, it appears to depend on where in the normal range you end up. A 2017 study combined data from 13 different studies with a total of 56,835 people who took thyroid hormone replacement therapy. The studies, on average, followed people for 12 years; the average age of participants was 64, and 60 percent were women. Thyroid levels were assessed by measuring both TSH (thyroid-stimulating hormone) and T4 (the thyroid hormone thyroxine).

Now, remember: A lower TSH is associated with a higher thyroid level.

The authors found that those with the lowest range of TSH (0.45-0.99 mIU/L) had a 24 percent increased risk of hip fracture compared to those with the highest range of TSH (3.5-4.49 mIU/L). Note that both of these groups were in the normal range, but those with the higher level of thyroid hormone had a greater risk. For non-hip fractures, the association with thyroid hormone intake and fracture risk was not as great, with an 8 to 10 percent increase in risk.

The study also found that higher levels of T4 were associated with an increased risk of fractures, a finding that has been corroborated in studies in both Europe and Taiwan.

Keep in mind that the studies have been of relatively short duration, so it's difficult to know how taking thyroid hormone may have affected you specifically. I wonder, however, about your current bone density. If it's low, you should consider supplementation with calcium, vitamin D and possibly a medication to help build up bone.

Regardless, I would try to take the lowest possible dose of thyroid hormone required to keep your thyroid levels on the lower end of normal. You should also make sure you walk and do weight-bearing exercises to help decrease your risk of osteoporosis.

As for supplements or lifestyle changes that promise to naturally boost thyroid hormone production, these are not reliable options. Nor will they reduce the risk for fractures. Stick with medications proven to work -- and at the lowest possible level.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Hello, dear readers! Spring is officially here, and the weather is mostly cooperating. (Like many of you, we were awed by the late-season snowstorms some of you had to cope with!) The change in seasons means fewer layers of clothes and more outdoor activities. With that in mind, we'd like to remind you to please use sunscreen, consider bug sprays to deal with the return of mosquitoes and ticks, and to ease into the return to physical activity to avoid injuries.

And now, onward.

-- A lot of you asked about Shingrix, the new shingles vaccine. For those of you age 50 and over, our answer is yes, please get vaccinated. The new vaccine was 96.6 percent effective in clinical trials, a significant improvement over the older vaccine, Zostavax. And, yes, even if you've had the older vaccine, the new guidelines recommend that you get vaccinated with Shingrix as well.

-- In a column about avoiding air pollution while walking for exercise in cities, we suggested seeking out areas with less traffic. However, a reader from Lincoln, Nebraska, worries this can put older adults at risk of becoming victims of robbery or assault. Instead, he recommends indoor malls, which actively encourage walkers.

"Our indoor mall marks the floor, so walkers can gauge how far they have walked," he writes. "They are then encouraged to have coffee or tea with a donut or roll at the mall after their walk. Thus, they are walking in a safe, air-conditioned area and also have a chance for social interaction."

-- We had an unusual letter from a reader in Terre Haute, Indiana, asking about the relationship between cannabis and spontaneous orgasms. The reader, who is 73 and uses cannabis to help with insomnia, said this has been happening to her for the last three months.

While there are several anecdotal accounts of spontaneous orgasms associated with cannabis, we were unable to locate any clinical research on the topic. We imagine that at some point, if this is indeed a widespread phenomenon, there will be a study or two to report on it.

-- A number of you are confused by the recent changes to blood pressure guidelines. Let us assure you that you're not alone. Part of the problem is that in the initial category for abnormal blood pressure, which is referred to as "elevated," the lower number (diastolic pressure) remains the same as the number for normal blood pressure.

What's happening is that the new guidelines consider blood pressure to be elevated even if only the systolic, or top number, exceeds its bracket. The bottom number can remain in "normal" territory and, due to the higher top number, be considered out of the normal range.

To clarify, here is the complete chart:

-- Normal: Less than 120/80

-- Elevated: Systolic between 120-129 and diastolic less than 80

-- Stage 1: Systolic between 130-139 or diastolic between 80-89

-- Stage 2: Systolic at least 140 or diastolic at least 90

-- Hypertensive crisis: Systolic over 180 and/or diastolic over 120

Thank you for the many kind and encouraging (and occasionally critical) notes you sent. We love this ongoing conversation with you and look forward to continuing it next time.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I recently had blood work done, and now my doctor says my liver enzymes are too high. How can I lower them? I have no symptoms, so I was surprised. I have never consumed alcoholic beverages, nor smoked. I am trying to lose some weight. I do frequently take ibuprofen for arthritis.

Dear Reader: I am not certain which of your liver enzymes are elevated, but the ones most often tested are AST (aspartate aminotransferase) and ALT (alanine aminotransferase). These enzymes are important for enzymatic reactions in the liver, but they are also a marker for liver inflammation and injury. We'll start with those.

An obvious cause for liver enzyme elevation is alcohol, which directly damages the cells of the liver. In such circumstances, AST is more elevated than ALT. But, as you said, you don't drink. Other possible causes include chronic infection with hepatitis B or C, or a genetic disorder called hemochromatosis, which leads to iron deposits in the liver. Tests for hepatitis infection and for iron and ferritin (a protein containing iron) levels can help diagnose or rule out these conditions.

Many medications can inflame the liver, such as statins for lowering cholesterol. Stopping the statin is often necessary to see if the liver enzymes come back down to normal. As for ibuprofen, it and other nonsteroidal anti-inflammatory drugs, or NSAIDs, rarely cause liver inflammation, but acetaminophen (Tylenol) does, especially at high doses (more than 4,000 milligrams per day). But again, the only way to determine a connection is to stop the medication and see if the enzymes return to normal.

Heart failure can be linked to liver enzyme elevation, as can cancers of the liver and cancers that metastasize to the liver. These conditions can be diagnosed through imaging procedures such as ultrasound and CT. Autoimmune conditions are a possibility as well; these are better diagnosed with specific blood tests.

But after ruling out these conditions, the most likely cause of liver enzyme elevation is non-alcoholic fatty liver disease, the most common liver disorder in the United States. A 2017 study of 6,000 adult men and women estimated the prevalence of fatty liver in the United States around 30 percent. The rise of this disease correlates with the rise of obesity and diabetes.

To diagnose fatty liver, you must rule out other causes for liver disease, with the first being alcohol consumption. After that, an ultrasound of the liver is a sensitive and simple way to diagnose the condition. An MRI, although costlier, is also a good test to diagnose the disease. Rarely, a liver biopsy is necessary to diagnose and evaluate the extent of fatty liver.

The best treatment for this condition is weight loss. Studies have shown significant improvements due to weight loss among those with fatty liver. To decrease both blood sugar and the storage of fat, choose a diet that is low in sugars and simple carbohydrates.

Eliminating sweets, sodas and juices would be a good start. If you're overweight or obese, try for a gradual weight loss of 1 to 2 pounds per week. Although you don't drink alcohol, those who do -- and who have elevated liver enzymes or fatty liver -- should give it up.

With a good diet and exercise, your liver enzymes should start to decline. But make sure to monitor them to ensure that's the case.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)