16.2 Diabetes, Thyroid Disease & Pubertal Disorders

Endocrinology is clinical category #14. CPNP-PC items reward pattern recognition and the next primary-care step, not starting growth hormone or a pump in clinic. New diabetes, thyroid disease, and pubertal timing are the high-yield cluster.

Quick Answer: Polyuria, polydipsia, and weight loss are type 1 diabetes until proven otherwise; DKA is an emergency. Screen at-risk adolescents for type 2 diabetes; refer all new diabetes to pediatric endocrinology. Hypothyroidism (Hashimoto, or congenital disease caught on newborn screen) presents with slowing: constipation, fatigue, poor linear growth, delayed puberty, brittle hair, sallow coarse skin — T4 and TSH first, not chromosomes. Precocious = girls <8, boys <9. Delayed = no thelarche by 13, no menarche by 15, no testicular enlargement by 14. Tanner stage before you order a karyotype.

Type 1 diabetes and DKA

Type 1 diabetes (T1D) is autoimmune beta-cell destruction. Classic new-onset is polyuria, polydipsia, weight loss, nocturia or secondary enuresis, and often candidiasis or blurred vision. Any age can present, including toddlers who look like they have a “stomach bug.” Diabetic ketoacidosis (DKA) adds vomiting, abdominal pain, Kussmaul respirations, fruity breath, dehydration, and lethargy or coma. That child leaves clinic in an emergency pathway for fluids and insulin — not with oral rehydration and a “follow up if not better.”

Do not wait for an A1c to come back next week when the point-of-care glucose is in the 300s and ketones are present. Diagnostic thresholds you should recognize: fasting glucose ≥126 mg/dL, random glucose ≥200 mg/dL with symptoms, 2-hour OGTT ≥200 mg/dL, A1c ≥6.5%. In a symptomatic child, a markedly elevated random glucose is enough to act. Antibody testing (GAD-65, IA-2, ZnT8, IAA) helps classify but does not delay emergency care.

Primary-care action: recognize, stabilize ABCs, send to an emergency setting experienced in pediatric DKA, and refer pediatric endocrinology for every new diagnosis. The CPNP-PC does not inaugurate outpatient insulin from a primary-care closet without a diabetes team. Education, glucagon, ketone rules, and school plans follow that referral.

Type 2 diabetes: screen the at-risk adolescent

Type 2 diabetes (T2D) clusters in adolescents with obesity, acanthosis nigricans, family history of T2D, maternal gestational diabetes, and signs of insulin resistance (hypertension, dyslipidemia, PCOS). It can still present with ketosis — obesity does not prove T2D and does not exclude DKA.

AAP/ADA-aligned screening: youth with overweight or obesity plus ≥1 risk factor, beginning at onset of puberty or age 10, whichever is earlier, and repeat about every 3 years (sooner if BMI is rising). Risk factors include first- or second-degree family T2D, high-prevalence race/ethnicity as used in ADA tables, acanthosis, maternal diabetes/GDM, and other insulin-resistance marks. Screening tests are fasting glucose, OGTT, or A1c as appropriate — not a random candy-bar glucose as your only strategy.

Lifestyle treatment is necessary and not sufficient as the only plan once diabetes is diagnosed. Refer pediatric endocrinology for new T2D as well as T1D: youth T2D progresses faster than adult T2D, and medication choices (metformin, insulin when ketosis or marked hyperglycemia is present, and other labeled agents) belong in a diabetes program. Primary care keeps comorbidity screening (lipids, ALT, BP, OSA, PCOS, microalbumin once directed) and family behavior work running in parallel.

Hypothyroidism: congenital versus Hashimoto

Congenital hypothyroidism is a newborn-screen emergency for the brain. Confirm with TSH and free T4 the same day an abnormal screen returns, and start levothyroxine urgently — days matter for neurodevelopment. Clinical clues if the screen was missed: prolonged jaundice, large fontanelle, macroglossia, hoarse cry, hypotonia, umbilical hernia, and later developmental delay. Do not wait for a 2-month well visit to “repeat the state lab.”

Acquired hypothyroidism in school-age children and adolescents is usually Hashimoto (autoimmune) thyroiditis: goiter, high TSH, low free T4, and often TPO antibodies. The primary-care picture is slowing and accumulation: constipation, fatigue, poor linear growth or short stature, weight gain, bradycardia, delayed sexual development, brittle hair, and sallow coarse dry skin. That constellation is a thyroid diagnosis until T4 and TSH say otherwise.

This is a classic PNCB discriminating item: an overweight 14-year-old with constipation, fatigue, delayed sexual development, short stature, brittle hair, and sallow coarse skin. Turner syndrome is in the delayed-puberty-plus-short-stature differential, but chromosomes are not the first test when myxedematous skin and hair and hypothyroid bowel and energy symptoms are painted in. The most useful laboratories are serum thyroxine (T4) and TSH. If thyroid function is normal, then you proceed to karyotype and the rest of the delayed-puberty pathway. If thyroid function is hypothyroid, treat and watch growth and puberty recover; you may still consider karyotype later if the story remains Turner-like, but you do not skip the thyroid.

Treat with levothyroxine and pediatric endocrine collaboration for congenital disease and for complicated acquired disease. Recheck TSH after dose changes; overtreatment is iatrogenic hyperthyroidism.

Hyperthyroidism (Graves)

Graves disease is the usual pediatric hyperthyroidism: suppressed TSH, high free T4/T3, goiter, tachycardia, widened pulse pressure, heat intolerance, tremor, lid lag, and deteriorating school focus that gets mislabeled ADHD. Weight loss with increased appetite is a clue. Refer endocrinology; primary care does not start methimazole as a casual experiment. Beta-blockade may be used for symptomatic tachycardia under specialist direction. Thyroid storm is an emergency.

Precocious puberty versus normal variants

Precocious puberty is secondary sexual development before age 8 in girls or before age 9 in boys. Age alone is not the whole item — sequence and tempo decide whether you reassure or refer.

Boys with true precocity and very young girls need a lower threshold for CNS imaging in the endocrine clinic because of the higher rate of intracranial lesions. Primary care’s job is to not call progressive, growth-accelerated puberty “just early” and to not MRI every 18-month-old with a transient breast bud.

Delayed puberty and constitutional delay

Delayed puberty: no thelarche by 13 in girls, no menarche by 15 (or no menarche by about 3 years after thelarche), no testicular enlargement by 14 in boys. Constitutional delay (“late bloomer”) is a diagnosis of pattern: family history of late puberty, delayed bone age, otherwise healthy child, and height that is short for age but appropriate for bone age and family. Pathologic delay: Turner syndrome, hypogonadotropic hypogonadism (including Kallmann with anosmia), chronic disease (celiac, IBD, CKD, anorexia, hypothyroidism), and primary gonadal failure.

Workup is staged: plot growth and Tanner, review nutrition and chronic disease, obtain bone age, and check TSH/T4 and other targeted labs. Karyotype in a short girl with delayed puberty is appropriate after you have not missed hypothyroidism — or immediately if classic Turner stigmata dominate without hypothyroid skin findings. Refer endocrine when the delay is pathologic, progressive, or unexplained.

Tanner staging, gynecomastia, lipomastia

You must be able to assign a Tanner stage, not merely recite that five exist.

• Girls: breast (thelarche) and pubic hair staged 1–5. Thelarche is the usual first sign. Peak height velocity is earlier in girls (around Tanner 2–3). Menarche typically follows thelarche by about 2–2.5 years.
• Boys: genital development 1–5. Testicular volume ≥4 mL (or length ≥2.5 cm) is the biologic start of puberty — not pubic hair, which can be adrenal. Peak height velocity is later (Tanner 3–4). An orchidometer in the drawer is a clinical tool, not a decoration.

Pubertal gynecomastia is a firm, mobile subareolar glandular disk, often slightly tender, peaking around Tanner 2–3, usually bilateral or asymmetric, and typically resolving within 1–2 years. Reassure, avoid drugs that worsen it when possible, and refer if prepubertal, rapidly progressive, large and persistent beyond about 2 years, or accompanied by hypogonadism or a testicular mass.

Lipomastia is adipose without a glandular disk — common in boys with obesity. Palpation distinguishes the two: pinch the subareolar tissue. Lipomastia tracks with weight; gynecomastia is gland. Do not promise that testosterone injections in primary care will melt either one.

Exam traps

• Sending new polyuria plus Kussmaul breathing home as viral gastroenteritis.
• Assuming every adolescent with obesity and hyperglycemia is T2D and delaying insulin when DKA is present.
• Karyotype before T4/TSH in the overweight, constipated, coarse-skinned, delayed-puberty teen.
• Calling isolated toddler thelarche central precocious puberty — or calling progressive 7-year-old thelarche with a growth spurt “normal.”
• Using pubic hair as the start of male puberty instead of testicular volume.
• Treating lipomastia as a surgical emergency or gynecomastia as obesity alone without palpating a disk.

Recognize diabetes as an emergency when it is, check the thyroid before the chromosomes when the skin and bowel say hypothyroidism, and stage puberty with your eyes and an orchidometer.