Endocrine Flashcards
What is the most common cause of hyperpituitarism? How does it present?
Pituitary adenoma. Presents based on the features of the hormone produced:
Prolactinoma - galactorrhea and amenorrhea in woman, headaches and loss of libido in men
Growth hormone cell adenoma - gigantism in kids, increased tongue, hand, feet, and jaw size in adults with increased organ size (heart problems) and potential DMII (GH induces liver gluconeogenesis)
ACTH tumor - Cushing syndrome
LH, FSH, and TSH tumors are less common
Most common pituitary adenoma? Treatment?
Prolactinoma
Bromocriptine or cabergoline (dopamine agonists) or surgery
How does a nonfunctional pituitary adenoma present?
Presentation due to mass effect: headaches, bitemporal hemianopsia (compression of optic chiasm) and hypopituitarism due to compression of normal pituitary tissue
How do you diagnose a GH tumor? What is the treatment?
GH and insulin growth factor - 1 (IGF-1 - released from liver by GH, what mediates growth of tissues) are elevated. There is a lack of suppression of GH with oral glucose.
Treatment is octreotide (somatostatin analog that suppress GH release), GH antagonists or surgery
Causes of hypopituitarism
- Pituitary adenoma (adults) or craniopharyngioma (children) due to mass effect or pituitary apoplexy (bleeding into adenoma)
- Sheehan syndrome
- Empty Sella syndrome
Central diabetes insipidus vs. Nephrogenic diabetes insipidus [causes and treatments]
Central - ADH deficiency due to hypothalamic or pituitary pathology. Loss of free water (hypernatremia, polydipsia, polyuria, low urine osmolality). Treatment: desmopressin (ADH analog)
Nephrogenic - unresponsiveness of the kidneys to ADH. Due to inherited mutation or drugs (Lithium, demeclocyline). Treatment: not responsive to desmopressin
What drug can cause SIADH? What are the other causes? What is the treatment?
Cyclophosphamide Ectopic production (small cell carcinoma of the lung), CNS trauma, pulmonary infection Treatment is free water restriction and demeclocyline (blocks ADH effects)
Clinical features of SIADH
Hyponatremia (normal 135-145), low serum osmolality
Metnal status changes and seizures - hyponatremia leads to neuronal swelling and cerebral edema (water shifts from vascular space to intracellular space)
What causes the increased basal metabolic rate in hyperthyroidism?
Increased synthesis of Na+/K+ ATPase
Hyperthryoidism - High or low cholesterol? High or low glucose levels?
Hypocholesterolemia (change in lipid metabolism)
Hyperglycemia
Graves disease is what type of hypersensitivity reaction?
Type II - autoantibody (IgG) that stimulates TSH receptor
What causes the pretibial myxedema and exophthalmos in graves?
Fibroblasts behind the eye and over the shin express TSH receptors -> TSH activation results in glycosaminoglycan (chondroitin sulfate and hyaluronic acid) build up, inflammation, fibrosis and edema
What is seen on histology with Graves disease?
Irregular follicles with scalloped colloid and chronic inflammation
What causes a thyroid storm? How does it present? What is the treatment?
Due to elevated catecholamines and massive hormone excess usually in response to stress (surgery or childbirth)
Presents as arrhythmia, hyperthermia, and vomiting with hypovolemic shock
Treatment includes PTU, beta blockers, and steroids
What is a multinodular goiter due to?
Relative iodine deficiency
Usually nontoxic, regions can become TSH independent leading to hyperthyroidism (rare)
What is a dyshormonogenetic goiter?
A form of cretinism due to a congenital defect in thyroid hormone production; most commonly involves thyroid peroxidase
Signs of cretinism
Mental retardation, short stature with skeletal abnormalities (thyroid hormone needed for normal brain skeletal development), coarse facial features, enlarged tongue and umbilical hernia
What is myxedema? What does it result in?
Accumulation of GAGs in the skin and soft tissue resulting in a deepening of voice and large tongue
What HLA is Hashimoto thryroiditis associated with? What antibodies are often present?
HLA-DR5
Antithryoglobulin and antithyroid peroxidase antibodies
What is seen histologically with Hashimoto?
Chronic inflammation (autoimmune destruction of thyroid gland) Germinal centers Hurthle cells (eosinophilic metaplasia of cells that line follicles)
Hashimoto thyroiditis - increased risk of what cancer?
B-cell (marginal zone) lymphoma
Presents as an enlarging thyroid gland late in disease course
What thyroiditis follows a viral infection and presents as a tender thyroid with transient hyperthyroidism?
Subacute granulomatous (De Quervain) thyroiditis
What thyroiditis presents as a non-tender ‘hard as wood’ thyroid with chronic inflammation?
Riedel fibrosing thyroiditis
What is a complication of Reidel fibrosing thyroiditis? Does it present as hyper or hypothyroid?
Fibrosis may extend to local structures and obstruct the airway
Hypothyroid
