T1 L9 HPA axis: clinical aspects Flashcards
What are the effects of glucocorticoids?
Maintenance of homeostasis during stress Anti-inflammatory Energy balance / metabolism Formation of bone and cartilage Regulation of blood pressure Cognitive function, memory, conditioning
Describe the circadian rhythm of cortisol levels
Rise during early morning
Peak just prior to awakening
Fall during the day
Low in the evening
What enzyme in the kidney inactivates cortisol?
11-B-HSD-2
What is Cushing’s syndrome?
Too much cortisol
What are the clinical features and symptoms of Cushing’s syndrome?
Weight gain Central obesity with thin arms and legs Fat deposition over upper back Rounded moon face Thin skin with easy bruising, pigmented striae Hirsutism Hypertension Insulin resistance Neuropsychiatric problems Osteoporosis
What are the causes of too much cortisol?
Pituitary adenoma: ACTH secreting cells
Adrenal tumour: adenoma
Ectopic ACTH: carcinoid, paraneoplastic
Iatrogenic: steroid treatment
What is Addison’s disease?
Too little cortisol
What are the clinical features and symptoms of too little cortisol?
Malaise, weakness, anorexia, weight loss
Increased skin pigmentation: knuckles, palmar creases, around mouth, pressure areas, scars
Hypotension / postural hypotension
Hypoglycaemia
What are the causes of too little cortisol?
Primary adrenal insufficiency: Addison’s disease, autoimmune, metastases, TB, decreased production of all adrenocortical hormones
Secondary to pituitary disease
Iatrogenic
Describe type I autoimmune polyendocrine syndromes
Rare
Onset in infancy
Ar (AIRE) gene
Common phenotype: Addison’s disease, hypoparathyroidism, candidiasis
Describe type II autoimmune polyendocrine syndromes
Commoner although still rare
Infancy to adulthood
Polygenic
Common phenotype: Addison’s disease, T1 diabetes, autoimmune thyroid disease
What are some autoimmune conditions that may occur together?
Type I diabetes Autoimmune thyroid disease Coeliac disease Addison's disease Pernicious anaemia Alopecia Vitiligo Hepatitis Premature ovarian failure Myasthenia gravis
What is the likely diagnosis of someone with type 1 diabetes mellitus with fatigue, weight loss and hypos?
Addison’s disease
What is the likely diagnosis of someone with type 1 diabetes and non-specific GI symptoms / diarrhoea?
Coeliac disease
What basal tests are done to assess the HPA axis?
Blood: cortisol, ACTH
Urine: cortisol
Saliva: cortisol
