Endocrinology Flashcards
Hormones
Chemical messengers that have an affect on organs via receptors
Hormone pathways
Autocrine = hormone acts upon the same cell it was released from
Paracrine = acts upon nearby cells
Endocrine = travels in the blood to act upon distant tissues
Hypothalamus
Integrates functions that maintain chemical and temperature homeostasis
Controls release of hormones from the anterior and posterior pituitary
Pituitary gland
- Anterior = releases TSH, ACTH, FSH, LH, growth hormone and prolactin
- Posterior = oxytocin, ADH
Pituitary tumours
The pituitary gland is located very close to the optic chiasm and so tumours often result in vision problems
Symptoms = headaches, vision changes, obstructive hydrocephalus, rhinorrhoea
Can result in hormone deficiencies or excesses
Cushing’s syndrome
Due to elevated cortisol levels
Symptoms = diabetes mellitus, increases susceptibility to infection, muscle wasting, facial/trunk obesity, depression
Diagnosis = urinary free cortisol, diurnal rhythm, dexamethasone suppression test
Dexamethasone suppression test
Dexamethasone completely suppresses cortisol release in healthy subjects
Acromegaly
Occurs in adults due to growth hormone excess
Symptoms = increase in hand/feet size, testicular atrophy
Diagnosis = oral glucose tolerance test, IGF-1 levels, MRI
Complications = diabetes, arthritis, erectile dysfunction, sleep apnoea, colon polyps
Female causes of infertility
- Ovulatory = cervical hostility, uterine malformation, infection, fallopian tube blockage
- Ovarian = PCOS, ovarian failure
- Other = Kallman’s syndrome, anorexia, pituitary destruction
Male causes of infertility
- Testicular = varicocele, tumour, torsion, orchitis, surgery
- Post-testicular = duct obstruction
- Other = Kallman’s syndrome, anorexia, pituitary destruction
Diabetes insipidus
Excretion of a large volume of hypotonic urine in absence of glycosuria
>4L per 24 hrs
Symptoms = polyuria, polydipsia, nocturia
Treatment = adequate water replacement
Hyperthyroidism
Symptoms = goitre, excess sweating, heat intolerance, palpitations, atrial fibrillation, heart failure, anxiety
Diagnosis = thyroid antibodies, radioactive iodine uptake scan
Hypothyroidism
Symptoms = tiredness, lethargy, weight gain, cold intolerance, bradycardia
Treatment = thyroxine replacement
Addison’s disease
Decreased adrenal cortex function due to physical damage or autoimmune diseases
Symptoms = hypoglycaemia, lethargy, weight loss
