Endocrinology COPY Flashcards
Answer: Hyperthyroidism
Answer: Option D
In hypothyroidism the thyroid test shows decreased uptake which is indicative of hypothyroidism.
A 69-year old man presents with granulomatosis with polyangiitis (formerly Wegener’s) diagnosed about 8 months ago. He was treated with rituximab and prednisalone for induction remission and has required prednisone since his diagnosis.
- O/E: Temperature is 37C, pulse is 80bpm, BP = 150/90mmHg, RR = 14bpm, O2 saturation is 99% on room air
- His physical examination is notable for the findings in Figures A and B.
What would be the most likely electrolyte abnormality found in this patient?
Answer: Hypokalemia and hypernatremia
- This patient has exogenous (iatrogenic) Cushing’s syndrome. Hypercortisolism is a result of prolonged glucocorticoid therapy, which is the most common cause of hypercortisolism.
- The mineralocorticoid effect of cortisol results in water and sodium retention, and increased K+ and H+ excretion.
- Patients with Cushing’s syndrome could also have the following:
- Hyperglycemia: due to stimulation of gluconeogenesis enzymes (e.g., glucose-6-phosphatase) and inhibition of glucose uptake in peripheral tissue
- Hyperlipidemia (hypercholesterolemia and hypertriglyceridemia)
- Leukocytosis (predominantly neutrophilic), eosinopenia, thrombocytosis
Answer: Exogenous corticosteroid use
Exogenous corticosteroid use causes Cushing’s syndrome. A negative feedback loop stops the secretion of ACTH from the anterior pituitary, and therefore both adrenal glands become atrophic from disuse.
ACTH-secreting adrenal adenoma, as well as hyperplasia or carcinoma, produce high cortisol. The offending adrenal gland will be enlarged and negative feedback loop causes suppression of ACTH from the anterior pituitary and therefore the other adrenal gland becomes atrophic.
ACTH-secreting pituitary adenoma causes both adrenal glands to enlarge → excess cortisol causes Cushing’s syndrome.
Ectopic ACTH syndrome → excess ACTH causes increase the size of both adrenal glands - > excess cortisol causes Cushing’s syndrome.
Answer: Anaplastic carcinoma
Answer: Progesterone
Answer: IGF-1
Acromegaly is caused by an excess of growth hormone from a pituitary adenoma. It is diagnosed by testing for elavated GH and insulin growth factor (IGF-1) levels as well as a lack of GH suppression during an oral glucose tolerance test.
Answer: Testosterone
Answer: Hashimoto’s thyroiditis
Hashimoto thyroiditis is part of the spectrum of autoimmune thyroid diseases (AITDs) and is characterized by the destruction of thyroid cells by various cell- and antibody-mediated immune processes.
Patients with Hashimoto thyroiditis have antibodies to various thyroid antigens, the most frequently detected of which include anti-thyroid peroxidase (anti-TPO), antithyroglobulin (anti-Tg), and to a lesser extent, TSH receptor-blocking antibodies (TBII). Nevertheless, a small percentage of patients with Hashimoto thyroiditis (approximately 10-15%) may be serum antibody negative.
Clinical pearl: Hashimoto thyroiditis is commonly clustered with other autoimmune diseases, including pernicious anemia, adrenal insufficiency, celiac disease, and type 1 diabetes mellitus; be on the lookout!
Answer: Difficulty driving due to reduced peripheral vision
Answer: Sheehan syndrome
Sheehan syndrome involves necrosis of the anterior pituitary secondary to infarction. The anterior pituitary is particularly vulnurable to infarction due to hyperplasia of lactotrophs (without an increase in blood supply) during pregnancy. Typically, the posterior pituitary is not affected due to its differing embryological origin and therefore blood supply.
Answer: Zona glomerulosa of adrenal cortex
Zona glomerulosa = aldosterone
Zona fasciculata = cortisol
Zona reticularis = androgens
This specimen was taken from a woman presenting with hypertension, who was later found to have high serum aldosterone and low serum renin. What is the likely diagnosis?
Answer: Conn’s syndrome (adrenal adenoma)
A left adrenal adenoma is shown. Primary hyperaldosteronism is most commonly caused by adrenal hyperplasia and Conn’s syndrome (adrenal adenoma).
Answer: Waterhouse-Friderichsen syndrome
The image shows the black-red of haemorrhagic necrosis of the adrenal glands caused by Waterhouse-Friderichsen syndrome. This is typically caused by sepsis and disseminated intravascular coagulation due to Neisseria meningitidis infection.
Answer: Secondary hyperaldosteronism
Answer: Cushing’s syndrome
Answer: Hashimoto’s thyroiditis
Answer: Bradycardia
Clinical features of hypothyroidism are based on decreased basal metabolic rate and decreased sympathetic nervous system activity. These include myxedema, weight gain despite normal appetite, muscle weakness, bradycardia, cold intolerance, and decreased sweating.
The other signs and symptoms listed are consistent with hyperthyroidism.
Answer: Hyperaldosteronism
Increased aldosterone increases the secretion of K+ (hypokalaemia) and H+ (metabolic alkalosis) and absorption of Na+ (hypernatremia) in the distal tubule and collecting duct. The increased Na+ leads to increased plasma volume (hypertension).
Answer: Antidiuretic hormone
Peptide hormones include: insulin, parathyroid hormone, ADH, oxytocin.
The others are steroid hormones.
Answer: Pregnenolone
Answer: Cushing’s syndrome
Answer: Thyroid gland
Answer: Cushing’s syndrome
Cushing’s syndrome (hypercortisolism) causes excess cortisol. At high levels, cortisol cross-reacts with mineralocorticoid receptors and can thereby activate Na+/K+ pumps as aldosterone would, resulting in the net loss of K+ to the urine via secretion.
Note respiratory alkalosis can cause hypokalaemia.
Answer: Chronic renal failure
Renal insufficiency leads to decreased phosphate excretion. The increased serum phosphate then binds free circulating calcium, leading to hypocalcemia and subsequent stimulation of the parathyroid glands.
Answer: Graves’ disease
Answer: Parathyroid adenoma
Parathyroid adenoma causes most cases of primary hyperparathyroidism. It is a benign neoplasm usually involving one gland and typically presents with asymptomatic hypercalcemia.
Answer: Phosphofructokinase 1
Answer: Rheumatoid arthritis
Answer: PTH directly activates osteoblast which indirectly activates osteoclast resulting in hypercalcemia and decrease in phosphate reabsorption in the proximal convoluted tubules
Answer: Dexamethasone suppression test
Answer: Hypothyroidism
Answer: Follicular carcinoma
Malignant proliferation of follicles surrounded by a fibrous capsule with invasion through the capsule.
Answer: Exogenous steroids
Answer: Neisseria meningitidis
Waterhouse-Friderichsen syndrome describes haemorrhagic necrosis of the adrenal glands.
Answer: Cushing’s syndrome
Answer: Thyrotoxicosis
Answer: The likely diagnosis is diabetes insipidus
Answer: Hyperkalaemia is a complication
Hyperkalaemia occurs as a result of low aldosterone levels.
Answer: Autoimmune involvement of retrobulbar connective tissue, as per Graves’ disease
In Graves’ disease, an IgG autoantibody binds to and stimulates TSH receptors in the thyroid. The TSH receptor is also expressed on fibroblasts behind the orbit and overlying the shin. Activation of these fibroblasts results in glycosaminoglycan build-up, inflammation, fibrosis, and oedema.