Endocrine Disorders and Joint Diseases
Rheumatic conditions commonly occur in endocrine disease. Nearly all hormones have as one of their targets the connective tissue cells. Hormones are involved in the development and function of connective tissue. If the components of a particular connective tissue are altered by abnormal hormonal influence, the physical properties of the connective tissue vary, and the functional capability of the tissue will change, creating recognizable illness.
Excessive production of growth hormone produces excessive growth in children (resulting in the child becoming a giant) or acromegaly (coarsening and enlargement of features) in adults. The arthritis of acromegaly is a distinct type of degenerative joint disease causing degeneration at the large joints associated with marked bony overgrowth and frequent back pain. Motion in joints is often preserved until late in the disease and excessive motion is common, particularly in the spine. Joint enlargement occurs because of fluid collections but also because of connective tissue overgrowth. Bony overgrowth is particularly prominent at the knuckles.
Later on, postural deformities occur with spinal curvature, bow legs, and loose joints. Characteristic changes occur in the skull, spine, hands, and other joints, and are visible on X-rays. Excessive thickness of the heel pad is also a prominent sign. Growth hormone causes an excessive number of cartilage cells, which causes overgrowth and cracking of cartilage, leading to degeneration of cartilage and overgrowth of bone near the joint. Acromegaly can also cause a muscle weakness and a neuropathy, (effect on the nerve), which may behave like connective tissue diseases.
Rheumatic conditions associated with the thyroid gland include:
Hypothyroid arthritis. Arthritis from an underactive thyroid gland is related to excessive deposits of certain proteins in connective tissues. Thyroid stimulating hormone, produced by the pituitary gland at the base of the brain, may cause the excessive protein collections. Symptoms include vague aches and pains, but usually there are no inflammatory signs. Joint thickening and fluid collections occur in 33% of patients. Knees, ankles, and small hand and foot joints are involved and are unusually thick. Knee x-rays show a characteristic thinning of bone near the joint.
Hypothyroid muscle disease. Muscle disease from an underactive thyroid gland is characterized by slow movements and delayed muscle contraction. Fifty percent of patients will complain of weakness, muscle cramping, pain and stiffness. Muscle enlargement is noted in 15 percent of patients, but muscle shrinkage is rare. Symptoms are aggravated by cold and inactivity. Chemicals from muscle tissue can be quite elevated in the blood. An EMG test (electromyogram) will demonstrate a characteristic abnormality. Examination of muscle tissue under the microscope shows typical changes.
Hypothyroid nerve disease. Nerve disease from an underactive thyroid may cause numbness or tingling. Carpal tunnel syndrome occurs in 5 to 10 percent of patients with hypothyroidism, causing numbness in the thumb, index, and middle fingers.
Hyperthyroidism. Thyroid acropachy is an unusual condition that follows treatment for Graves disease, a type of thyroid overactivity in a small percentage of patients with an overactive thyroid gland. This causes rounding of the finger and toenails, inflammation of the digits and distal extremities, and swelling of soft tissues. It is frequently associated with bulging eyes and a rash on the legs, and often causes pain in the bones.
Bursitis in hyperthyroidism. Bursitis, particularly of the shoulder joint, commonly occurs with an overactive thyroid gland. It may also occur surrounding other joint areas. Joint areas show thickening and soft tissue swelling, and there is significant limitation of motion of joints. Symptoms often improve after treatment of the overactive thyroid.
Hyperthyroid muscle disease. Hyperthyroid muscle disease takes several forms. Diffuse muscle disease is not uncommon with an overactive thyroid gland. This frequently causes thigh muscle weakness that may be mild or severe. Shrinkage of muscle and collection of fat in the muscles does occur. Muscle chemicals in the blood are generally normal. Paralysis of the eye muscles may exist. Swelling of the eyelids and the other layers of the eye, and eye nerve inflammation, are not unusual.
Lupus-like conditions. Several medications used to treat an overactive thyroid gland, especially propylthiouracil, and the thionamides, may cause a lupus-like condition.
Osteoporosis. Osteoporosis (thin brittle bones) may occur in thyroid disease because of a loss of calcium and phosphorus from the body.
Hashimoto's thyroiditis. This condition is an autoimmune process affecting the thyroid gland. Patients have an overactive thyroid early, but 50 percent develop an under active thyroid gland at a later time. Other rheumatic diseases, such as rheumatoid arthritis or lupus can be seen in the same patients. Vitiligo (loss of skin pigment in some areas) is a commonly associated finding.
Rheumatic conditions associated with the pancreas include:
DISH. A severe form of spinal wear-and-tear arthritis known as diffuse idiopathic skeletal hyperostosis (DISH) occurs in approximately 13 percent of diabetics. Symptoms are usually minimal but most often involve the middle spine. X-rays demonstrate a large amount of bony overgrowth.
Diabetic charcot arthritis. This is a destructive arthritis occurring because the diabetic does not have good sensation in a particular area. It involves the feet, ankles, knees and spine. Typical findings are created by a combination of small fractures, lack of blood flow, and infection. This causes eventual collapse of the foot structures with a poor gait and disposes the patient to ulcers and calluses.
Diabetic dissolving bone. Dissolving bone occurs even without evidence of local nerve disease or poor circulation. There is a patchy or general loss of bone involving the feet, toes, or fingers. Severe pain may be present. The diabetes may be mild or undiagnosed. The X-ray findings could resemble those seen in rheumatoid arthritis. This may progress to complete dissolution of bone, but may also heal completely.
Soft tissue contracture syndromes. Dupuytren's contracture (a tightening of tendons in the palm) occurs in 15 percent of diabetics. Diabetic wrist stiffness has recently been described in up to 40 percent of diabetics with juvenile onset diabetes. This creates a contracture deformity of the fingers and knuckles, particularly of the 4th and 5th digits. Trigger finger is quite frequently seen in diabetics.
Other types of arthritis in diabetes. About 15 percent of diabetics have calcium deposits develop in their joint cartilage that represents scar tissue. In addition, there is some questionable relationship between diabetes and gout. Probably, the common bond is obesity and high cholesterol. Generalized primary osteoarthritis is somewhat more common in diabetics. In addition, bursitis of the shoulder, particularly with bilateral involvement, is not uncommon in diabetes. It is more common in insulin dependent diabetics and in females, and most often involves the non-dominant side. It may be followed by development of frozen shoulder.
Bone disease from overactive parathyroid glands in the neck causes early dissolving of bone. Destructive arthritis also occurs in hyperparathyroidism, involving the wrists and knees particularly, with development of holes at the edges of the bone near the joints. The primary problem is softening of bone, with cartilage thinning and stiffness secondary. In many patients with hyperparathyroidism, gout and pseudogout may also occur.
Muscle weakness or abnormal nerve function that causes fatigue, particularly of the lower extremities, also occurs with an overactive parathyroid gland.
The physician must consider all of these possible gland abnormalities when the patient complains of symptoms arising from the muscles, bones, or joints. He or she must then select appropriate tests to prove or eliminate these possible diagnoses.
If medical therapy fails, surgical procedures such as sympathectomy could be considered, along with continued drug therapy.