PEDIATRIC ENDOCRINE DISORDERS 1.3 (TB)

Question 1

What are the principal regulators of calcium homeostasis?

Answer 1

Parathyroid hormone (PTH) and vitamin D

Question 2

Which hormones are important primarily in the fetus?

Answer 2

Calcitonin and PTH-related peptide (PTHrP)

Question 3

Where is PTH synthesized?

Answer 3

Chief cells of the parathyroid gland

Question 4

What stimulates PTH secretion?

Answer 4

Hypocalcemia

Question 5

What is the effect of PTH on serum calcium and phosphate?

Answer 5

Increases serum Ca2+ and lowers serum PO4

Question 6

How does vitamin D affect calcium and phosphate levels?

Answer 6

Increases absorption and serum levels of both Ca2+ and PO4

Question 7

Where is calcitonin synthesized?

Answer 7

Parafollicular cells of the thyroid gland

Question 8

What is the effect of calcitonin on bones?

Answer 8

Inhibits osteoclast activity. decreasing resorption of Ca2+

Question 9

When do calcitonin levels increase?

Answer 9

In response to hypercalcemia

Question 10

What are common causes of early neonatal hypocalcemia?

Answer 10

Prematurity. asphyxia. infants of diabetic mothers

Question 11

When does late neonatal hypocalcemia occur?

Answer 11

After 2nd to 3rd day and during the first week of life

Question 12

What is transient idiopathic hypocalcemia?

Answer 12

Hypocalcemia in 1-8 weeks of age with low serum PTH

Question 13

What syndrome is associated with parathyroid gland aplasia or hypoplasia?

Answer 13

DiGeorge / velocardiofacial syndrome

Question 14

What genetic pattern does X-linked recessive hypoparathyroidism follow?

Answer 14

Familial. onset with afebrile seizures in infants 2 weeks to 6 months

Question 15

What features are seen in autosomal recessive hypoparathyroidism with dysmorphic features?

Answer 15

Microcephaly. deep-set eyes. beaked nose. micrognathia. large floppy ears. growth restriction. cognitive impairment

Question 16

What gene is mutated in hypoparathyroidism with deafness and renal anomaly syndrome?

Answer 16

GATA3

Question 17

What causes neonatal suppression of PTH secretion?

Answer 17

Maternal hyperparathyroidism

Question 18

What mutation is found in autosomal dominant hypoparathyroidism?

Answer 18

Activating mutation in the calcium-sensing receptor

Question 19

What condition is associated with mitochondrial DNA mutations and hypoparathyroidism?

Answer 19

Kearns-Sayre syndrome. MELAS. mitochondrial trifunctional protein deficiency

Question 20

What is APECED?

Answer 20

Autoimmune Polyendocrinopathy. Candidiasis and Ectodermal Dystrophy

Question 21

What is idiopathic hypoparathyroidism?

Answer 21

Hypoparathyroidism with no identifiable cause

Question 22

What is the pathogenesis of hypoparathyroidism?

Answer 22

↓ PTH → ↓ serum Ca2+ and ↑ phosphate levels

Question 23

What causes tetany in hypocalcemia?

Answer 23

Uninhibited activity of voltage-gated sodium channels and increased neuromuscular irritability

Question 24

What lab values are expected in hypoparathyroidism?

Answer 24

Low serum Ca (5-7 mg/dL). elevated phosphate (7-12 mg/dL). low PTH

Question 25

What are radiographic findings in hypoparathyroidism?

Answer 25

Metaphyseal bone density. basal ganglia calcifications

Question 26

What is the mnemonic for hypocalcemia features?

Answer 26

SPASMODIC

Question 27

What does SPASMODIC stand for?

Answer 27

Spasm. Perioral paresthesia. Anxious. Seizures. Muscle tone ↑. Orientation impaired. Dermatitis

Question 28

What is the treatment for acute hypocalcemia?

Answer 28

IV calcium gluconate 5-10 mL of 10% solution at 0.5–1.0 mL/min

Question 29

What is the maintenance treatment for hypoparathyroidism?

Answer 29

Calcitriol and oral calcium

Question 30

What condition presents as hypocalcemia with elevated PTH?

Answer 30

Pseudohypoparathyroidism

Question 31

What is Albright hereditary osteodystrophy?

Answer 31

Pseudohypoparathyroidism with skeletal abnormalities

Question 32

What defect is found in pseudohypoparathyroidism type 1a?

Answer 32

GNAS1 gene (Gsα protein)

Question 33

What are physical features of type 1a pseudohypoparathyroidism?

Answer 33

Short stocky build. round face. brachydactyly

Question 34

What test confirms pseudohypoparathyroidism type 1a?

Answer 34

Blunted cAMP and phosphate response to synthetic PTH

Question 35

What differentiates type 1b from type 1a PHP?

Answer 35

Type 1b has renal resistance only and normal appearance

Question 36

What is acrodysostosis with hormone resistance?

Answer 36

A condition resembling PHP 1a without Gsα defects. with metaphyseal dysplasia

Question 37

What is primary hyperparathyroidism caused by?

Answer 37

Adenomas or hyperplasia of the parathyroid glands

Question 38

What conditions are associated with primary hyperparathyroidism?

Answer 38

MEN syndromes and hyperparathyroidism-jaw tumor syndrome

Question 39

What causes secondary hyperparathyroidism?

Answer 39

Hypocalcemia from vitamin D deficiency. malabsorption or chronic renal disease

Question 40

What causes neonatal severe hyperparathyroidism?

Answer 40

Mutations in calcium-sensing receptor gene

Question 41

What causes transient neonatal hyperparathyroidism?

Answer 41

Infants born to mothers with untreated hypo- or pseudohypoparathyroidism

Question 42

What lab values are elevated in hyperparathyroidism?

Answer 42

Serum calcium. nonprotein nitrogen. uric acid. intact PTH

Question 43

What are radiographic findings in hyperparathyroidism?

Answer 43

Subperiosteal bone resorption. granular skull. absent lamina dura. renal stones

Question 44

What are clinical signs of hyperparathyroidism?

Answer 44

Muscle weakness. fatigue. GI symptoms. polyuria. psychiatric symptoms

Question 45

What is parathyroid crisis?

Answer 45

Serum calcium >15 mg/dL with oliguria. stupor. coma

Question 46

What is the treatment for hyperparathyroidism?

Answer 46

Surgical exploration and removal of affected glands

Question 47

What medications can be used in hyperparathyroidism?

Answer 47

Bisphosphonates and calcimimetics

Question 48

What is a risk after parathyroidectomy?

Answer 48

Postoperative hypocalcemia and tetany

Question 49

What is the cardinal biochemical feature of diabetes mellitus?

Answer 49

Hyperglycemia

Question 50

What differentiates major forms of diabetes?

Answer 50

Insulin deficiency vs insulin resistance

Question 51

What causes Type 1 diabetes mellitus (T1DM)?

Answer 51

Deficiency of insulin secretion due to pancreatic β-cell damage

Question 52

What causes Type 2 diabetes mellitus (T2DM)?

Answer 52

Insulin resistance at skeletal muscle, liver, and adipose tissue with varying β-cell impairment

Question 53

What is T1DM also known as?

Answer 53

Insulin-dependent diabetes mellitus or juvenile diabetes

Question 54

What characterizes T1DM?

Answer 54

Low or absent endogenous insulin and dependence on exogenous insulin

Question 55

What is the most common endocrine-metabolic disorder of childhood?

Answer 55

Type 1 diabetes mellitus (T1DM)

Question 56

What gene is most strongly associated with T1DM?

Answer 56

MHC class II genes, specifically HLA DR3/DR4

Question 57

Name environmental factors that may trigger T1DM.

Answer 57

Viral infections, congenital rubella, enteroviruses, mumps, hygiene hypothesis, diet, microbiome, stress

Question 58

What is the 'honeymoon period' in T1DM?

Answer 58

Partial remission of disease when some β-cells still produce insulin

Question 59

What are the stages in the natural history of T1DM?

Answer 59

Initiation of autoimmunity, preclinical autoimmunity, clinical disease, remission, established disease, complications

Question 60

What fasting plasma glucose level indicates impaired fasting glucose?

Answer 60

100–125 mg/dL (5.6–7.0 mmol/L)

Question 61

What 2-hour OGTT value indicates impaired glucose tolerance?

Answer 61

≥140 mg/dL but <200 mg/dL

Question 62

What is the HbA1c range for prediabetes?

Answer 62

5.7–6.4% (39–47 mmol/mol)

Question 63

What fasting plasma glucose level indicates diabetes?

Answer 63

≥126 mg/dL (7.0 mmol/L)

Question 64

What 2-hour OGTT value confirms diabetes?

Answer 64

≥200 mg/dL (11.1 mmol/L)

Question 65

What HbA1c value confirms diabetes?

Answer 65

≥6.5% (48 mmol/mol)

Question 66

What is a classic triad of T1DM symptoms?

Answer 66

Polyuria, polydipsia, polyphagia

Question 67

What are additional common symptoms of T1DM?

Answer 67

Weight loss, fatigue, malaise, DKA symptoms

Question 68

What is the initial insulin dose for a prepubertal child without DKA?

Answer 68

0.25–0.50 units/kg/day

Question 69

What is the insulin dose for a pubertal child with DKA?

Answer 69

1.0–1.2 units/kg/day

Question 70

What characterizes Type 2 diabetes mellitus (T2DM)?

Answer 70

Insulin resistance with progressive non-autoimmune β-cell failure

Question 71

Which ethnic groups are at higher risk for T2DM?

Answer 71

Native Americans > Hispanic Americans > African-Americans > White Americans

Question 72

What skin sign is common in T2DM?

Answer 72

Acanthosis nigricans

Question 73

What is the cornerstone of T2DM treatment in children?

Answer 73

Healthy lifestyle interventions and metformin

Question 74

What are diagnostic criteria for DKA?

Answer 74

Glucose >250 mg/dL, pH <7.3, bicarbonate <15 mEq/L, ketonemia/ketonuria

Question 75

What are clinical signs of DKA?

Answer 75

Dehydration, nausea, vomiting, lethargy, Kussmaul respirations, fruity breath, coma

Question 76

What causes acidosis in DKA?

Answer 76

Accumulation of keto acids like β-hydroxybutyric acid and acetoacetic acid

Question 77

What is a typical insulin infusion rate for DKA?

Answer 77

0.1 units/kg/hr

Question 78

When should D5 be used in DKA management?

Answer 78

When glucose falls below ~300 mg/dL

Question 79

What is the function of the 2-bag system in DKA?

Answer 79

To titrate dextrose concentration between 0% and 10%

Question 80

When can insulin infusion rate be decreased in DKA?

Answer 80

If glucose falls below 100 mg/dL despite D10 fluids