Your doctor did a very nice work up. Most likely it is nothing and it will be normal on repeat exam. Keep up the regular exercise!

Good luck!

She is on the right track, isolatedALT, without AST, get, and no other symptoms warrants repeating test. But I will do complete and more profound analysis and more detailed Hx and exam and not rely on tests. 95 of diseases are diagnosed by H& P and a good ram, including travel, visitors, recent sickness, chest pain. I recommend EKG.

Here are the highlights of an eMedicineHealth article that fully answers your question. For more details, just follow the link below. This will probably explain why your doctor could not just give you one concrete answer. She has to rule out a lot of other options before settling for the suggestion of heavy metal poisoning, Hepatitis C or hepatic cancer, which are all notorious for very high levels of ALT and AST.

Diseases That Cause Abnormal Aminotransferase Levels

The most common diseases causing abnormally elevated ALT and AST are:

Acute viral hepatitis, such as hepatitis A or B

Chronic viral hepatitis, such hepatitis B or C

Cirrhosis of the liver (scarring of the liver due to long standing inflammation of the liver)

Liver damage from alcohol abuse or alcoholic fatty liver

Hemochromatosis (a genetic condition causing long standing liver damage due to iron build up in the liver)

Diminished blood flow to the liver (from shock or heart failure)

Medications That Cause Abnormal Aminotransferase Levels

Intentional medication overdose, such as acetaminophen (Tylenol liver damage)

Acetaminophen (Tylenol or other medications with a Tylenol component, such as Vicodin)

Some pain medications, or example, diclofenac (Voltaren) and naproxen (Naprosyn, Anaprox, Aleve, Naprelen)

Cholesterol-lowering medications, statins, for example, atorvastatin (Lipitor) and simvastatin (Zocor).

Some antibiotics, for example, sulfonamides and nitrofurantoin (Macrodantin; Furadantin; Macrobid)

Some tuberculosis medications, for example, isoniazid (Nydrazid, Laniazid, INH)

Some anti-fungal medications, for example, fluconazole (Diflucan) and itraconazole (Sporanox)

Some psychiatric medications, for example, tricyclic antidepressants

Some seizure medications, for example, phenytoin (Dilantin), carbamazepine (Tegretol, Tegretol XR , Equetro, Carbatrol), and valproic acid (Depakote, Depakote ER, Depakene, Depacon) Continue Reading

Less Common Causes of Abnormal Aminotransferase Levels

There are many other causes of the abnormally elevated blood liver enzyme levels in addition to those mentioned above. Some of these conditions include the following:

Wild mushroom poisoning

Wilson's disease, due to excess buildup of copper in the liver

Metastatic cancer to the liver (cancer spread from another organ to the liver)

Cancer of the liver (hepatocellular carcinoma)

Auto-attack immune hepatitis (the body's own immune system attack the liver cells)

Pregnancy

Inflammatory bowel disease such as Crohn's disease or ulcerative colitis

Gallstones

Obesity, which can cause infiltration of fat into liver cells causing inflammation (called fatty liver or steatohepatitis)

Alpha-1-antitrypsin deficiency Continue Reading

Source: eMedicineHealth

http://www.emedicinehealth.com/liver_blood_tests/article_em.htm

It can be various things.

Liver damage from conditions such as hepatitis or cirrhosis.

Lead poisoning.

Exposure to carbon tetrachloride.

Many medicines, such as statins, antibiotics, chemotherapy, aspirin, narcotics, and barbiturates.

Mononucleosis

Vigorous exercise

exercise does it

ALT level could rise for a number of different reasons; including after joint or muscle injuries .