Patho: Chapter 41 (Endocrine disorders, Diabetes Mellitus, and the metabolic syndrome)

What is a primary endocrine disorder?

A disorder caused by an abnormality in the peripheral (target) endocrine gland.

What is a secondary endocrine disorder?

A disorder caused by an abnormality in the anterior pituitary gland.

What is a tertiary endocrine disorder?

A disorder caused by an abnormality in the hypothalamus.

What causes idiopathic growth hormone (GH) deficiency in children?

A lack of hypothalamic growth hormone-releasing hormone (GHRH) despite having adequate somatotropes in the anterior pituitary.

Do children with pituitary tumors or agenesis of the pituitary lack somatotropes?

Yes

What are somatropes?

Specialized cells in the anterior pituitary that synthesize and secrete growth hormone (GH).

What is Laron-type dwrafism?

A rare form of short stature caused by resistance to growth hormone, resulting in impaired linear bone growth

What causes Laron-type dwarfism?

An abnormal growth hormone (GH) receptor that causes resistance to GH.

What are the characteristics/manifestations of Laron-type dwarfism?

What is gigantism?

Excessive linear bone growth that occurs before puberty

What causes gigantism?

Excess growth hormone secretion before epiphyseal closure (before puberty).

What is acromegaly?

Excessive growth of soft tissues and bone that occurs after epiphyseal closure (after puberty).

What is the most common cause of acromegaly?

A GH-secreting pituitary adenoma (benign pituitary tumor)

What are the characteristics/manifestations of acromegaly?

• Enlarged hands and feet

• Broad nose

• Protruding jaw

• Hunchback

• Overgrowth of cartilage (ears, nose)

• Degenerative arthritis

• Enlargement of heart and other organs

• Hypertension

• Atherosclerosis

What are the metabolic effects of excess GH?

• Insulin resistance

• Impaired glucose regulation

• Diabetes mellitus

• Increased lipolysis and fatty acid use

What is hypothyroidism?

A condition characterized by decreased thyroid hormone levels and a decreased metabolic rate.

What are the characteristics/manifestations of hypothyroidism?

• Mental and physical sluggishness

• Myxedema

• Somnolence

• Decreased cardiac output

• Bradycardia

• Constipation

• Decreased appetite

• Hypoventilation

• Cold intolerance

• Weight gain

What causes hypothyroidism in an infant?

• Congenital absence of the thyroid gland

• Abnormal biosynthesis of thyroid hormone

• Deficient TSH secretion

What can untreated congenital hypothyroidism cause?

• Intellectual disability

• Impaired physical growth

Why does an infant who lacks a thyroid gland appear normal at birth?

Thyroid hormones were supplied by the mother during fetal development

What is the first sign of a congenital lack of a thyroid gland?

Prolonged physiologic jaundice

What are the characteristics/manifestations of congenital hypothyroidism?

• Prolonged physiologic jaundice

• Respiratory difficulties

• Hoarse cry

• Enlarged tongue

• Feeding difficulties

• Lack of interest/activity

• Enlarged abdomen

What is cretinism?

The intellectual disability and impaired physical growth that results from untreated congenital hypothyroidism

What cells secrete insulin?

Beta cells of the pancreatic islets (islets of Langerhans)

What cells secrete glucagon?

Alpha cells of the pancreatic islets (islets of Langerhans)

What does insulin stimulate?

• Glucose uptake, use, and storage

• Glycogenesis (glucose → glycogen)

• Lipogenesis (glucose → fat)

• Protein synthesis

What does insulin inhibit>

• Glycogenolysis (glycogen breakdown)

• Lipolysis (fat breakdown)

• Gluconeogenesis (protein breakdown → glucose production)

What does glucagon do?

• Increases blood glucose levels

• Stimulates glycogenesis (glucose → glycogen)

• Stimulates lipogenesis (glucose → fat)

• Stimualtes (amino acids → glucose)