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Symptoms of endocrine disease
SYMPTOMS OF ENDOCRINE DISEASE
Symptoms of endocrine disease
Hyperfunction Causes: hyperfunction generally results from over-secretion of a hormone from a tumour that becomes autonomous, or as a result of failure of suppression of production of the hormone. The immune system can cause hyperfunction when antibody binds to and stimulates the thyroid-stimulating hormone receptor (Graves’ disease).
Karim Meeran
Clinical features: symptoms of hyperfunction are organ specific and are discussed in the relevant contributions to the Endocrine Disorders chapter of MEDICINE.
Hormone concentrations can vary widely in an attempt to regulate for changes in the environment. Their levels are often regulated by negative feedback, which usually results in tight control of a system. One difficulty in diagnosing endocrine disease is that hormone levels may be in the published ‘reference range’, even in patients with significant disease. This is because the concentration of hormones should vary depending on other, extraneous factors, and the normal range does not take account of this. Thus, hyperfunction can be missed because the measured levels remain within the reference range. In primary hyperparathyroidism, for example, the concentration of parathyroid hormone may be within the reference range despite high calcium levels, though it should be suppressed; the fact that it is not confirms primary hyperparathyroidism. In Cushing’s disease, cortisol and adrenocorticotrophic hormone may both be within the reference range. Diagnosis in endocrine disorders therefore relies on dynamic tests, usually performed at a defined time of day. Although a random growth hormone (GH) level is usually unhelpful in the diagnosis of acromegaly, GH measured during an oral glucose tolerance test is likely to be helpful. Problems occur when the regulation of hormone production fails. This can result in hyperfunction (Figure 1) or hypofunction (Figure 2).
Investigations: a suppression test is more likely to demonstrate hyperfunction than a static test. The only indication of hyperfunction might be non-suppressibility of the hormone concerned, and if this is suspected, referral to an endocrine unit is essential. It is generally not possible to interpret hormone measurements outside defined parameters. Endocrinologists are often asked whether a patient in the ICU may have an endocrine disorder such as Cushing’s disease or phaeochromocytoma, but it is usually impossible to make such a diagnosis while the individual is an in-patient.
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Hypofunction Causes: hypofunction commonly results from autoimmune damage to the endocrine organ (as in primary hypothyroidism, gonadal failure and Addison’s disease). In the case of the pituitary, which is enclosed in a bony case, the pressure caused by a tumour can cause the cells to fail. Hypofunction can also be iatrogenic, when an endocrine organ is removed or destroyed, or as the result of drug treatment that suppresses hormone production. Clinical features: the onset of hypofunction is usually gradual and patients often fail to notice any change. Lethargy, tiredness and depression are common consequences of endocrine hypofunction, and the diagnosis is often missed, particularly because of the rarity of endocrine causes compared with other causes of such symptoms. Investigations: dynamic tests are useful in patients with endocrine failure, and stimulation tests are essential. Serum cortisol may be within the reference range in patients with pituitary failure caused by pituitary adenoma, but may not increase adequately under stress. During times of metabolic stress, an adequate cortisol response is essential for normal functioning.
Karim Meeran is Senior Lecturer and Consultant Endocrinologist at Charing Cross and Hammersmith Hospitals, London, UK.
MEDICINE 33:11
2
1
© 2005 The Medicine Publishing Company Ltd
Symptoms of endocrine disease
Hyperfunction Causes: hyperfunction generally results from over-secretion of a hormone from a tumour that becomes autonomous, or as a result of failure of suppression of production of the hormone. The immune system can cause hyperfunction when antibody binds to and stimulates the thyroid-stimulating hormone receptor (Graves’ disease).
Karim Meeran
Clinical features: symptoms of hyperfunction are organ specific and are discussed in the relevant contributions to the Endocrine Disorders chapter of MEDICINE.
Hormone concentrations can vary widely in an attempt to regulate for changes in the environment. Their levels are often regulated by negative feedback, which usually results in tight control of a system. One difficulty in diagnosing endocrine disease is that hormone levels may be in the published ‘reference range’, even in patients with significant disease. This is because the concentration of hormones should vary depending on other, extraneous factors, and the normal range does not take account of this. Thus, hyperfunction can be missed because the measured levels remain within the reference range. In primary hyperparathyroidism, for example, the concentration of parathyroid hormone may be within the reference range despite high calcium levels, though it should be suppressed; the fact that it is not confirms primary hyperparathyroidism. In Cushing’s disease, cortisol and adrenocorticotrophic hormone may both be within the reference range. Diagnosis in endocrine disorders therefore relies on dynamic tests, usually performed at a defined time of day. Although a random growth hormone (GH) level is usually unhelpful in the diagnosis of acromegaly, GH measured during an oral glucose tolerance test is likely to be helpful. Problems occur when the regulation of hormone production fails. This can result in hyperfunction (Figure 1) or hypofunction (Figure 2).
Investigations: a suppression test is more likely to demonstrate hyperfunction than a static test. The only indication of hyperfunction might be non-suppressibility of the hormone concerned, and if this is suspected, referral to an endocrine unit is essential. It is generally not possible to interpret hormone measurements outside defined parameters. Endocrinologists are often asked whether a patient in the ICU may have an endocrine disorder such as Cushing’s disease or phaeochromocytoma, but it is usually impossible to make such a diagnosis while the individual is an in-patient.
1
Hypofunction Causes: hypofunction commonly results from autoimmune damage to the endocrine organ (as in primary hypothyroidism, gonadal failure and Addison’s disease). In the case of the pituitary, which is enclosed in a bony case, the pressure caused by a tumour can cause the cells to fail. Hypofunction can also be iatrogenic, when an endocrine organ is removed or destroyed, or as the result of drug treatment that suppresses hormone production. Clinical features: the onset of hypofunction is usually gradual and patients often fail to notice any change. Lethargy, tiredness and depression are common consequences of endocrine hypofunction, and the diagnosis is often missed, particularly because of the rarity of endocrine causes compared with other causes of such symptoms. Investigations: dynamic tests are useful in patients with endocrine failure, and stimulation tests are essential. Serum cortisol may be within the reference range in patients with pituitary failure caused by pituitary adenoma, but may not increase adequately under stress. During times of metabolic stress, an adequate cortisol response is essential for normal functioning.
Karim Meeran is Senior Lecturer and Consultant Endocrinologist at Charing Cross and Hammersmith Hospitals, London, UK.
MEDICINE 33:11
2
1
© 2005 The Medicine Publishing Company Ltd