Category Archives: Endocrinology

Micropenis

In neonates and infants, the stretched penile length is at least 2cm in 97% of boys.

Micropenis describes a shorter penis than this, that is otherwise of normal form. Penis needs to be stretched out, and suprapubic fat pad pushed in.

Causes are hypogonadotrophic (Kallman’s syndrome, Laurence-Moon-Biedel-Bart, Prader-Willi) or hypogonadism (anorchia or testicular dysgenesis, Trisomy 21, Noonans, Klinefelter). May be part of more complex syndrome.

Differential is intersex, “buried penis” due to suprapubic fat pad (usually obese), chordee.

Neat trick is to modify a 10ml syringe by cutting off needle end and inserting plunger into cut end. Gives you scale and stretches penis!

[https://dx.doi.org/10.4274%2FJcrpe.1135]

Delayed puberty

Note puberty lines on RCPCH growth charts, for starting puberty (girls 8), delayed beginning (girls 13, boys 14) and completing (girls 16, boys 17).  Delayed completion (especially menses) also needs investigation.  Also a shaded triangle for short boys and girls during this time, to remind that probably ok if puberty not yet started, but potentially a problem if nearly completing.

In girls, rule out Turner’s syndrome.

Otherwise look for evidence of dysmorphism, that might suggest another chromosomal or genetic issue, and evidence for broader pituitary issue (midline facial defects, visual defects, poor growth, child looks younger than their age).

If not central, then must be gonadal issue – check testes, do USS scan to look at ovaries.

Blood tests then to assess pituitary hormones, particularly FSH/LH, plus oestradiol and testosterone.

In girls with amenorrhoea but normal pubertal progression, haematocolpos due to imperforate hymen presents with abdominal pain, urinary retention.

Cushing’s disease

Excessive cortisol due to an ACTH secreting tumour. In children, Cushing’s syndrome usually due to steroid treatment.

Manifests as dramatic weight gain, usually with angry striae, growth arrest (in terms of height), change in facial appearance, buffalo hump, hypertension.

These findings are hard to spot given that obesity with striae (and hypertension) in children common. Main clue is height centile below mean (and below MPH). Delayed bone age also a clue, as both of these things tend to be above normal in obese children.

Investigation is tricky as pituitary adenomas are not always seen on MRI and petrosal sinus sampling for cortisol is sometimes required! Even exclusion is tricky, requiring 24hr urinary cortisol collection over 3 days, low dose dexamethasone suppression testing.

CRH test done as part of work up, to see if ACTH is ectopic, which is exceptionally rare. Increased response to CRH test is almost diagnostic for Cushing’s though! High dose dexamethasone suppression rarely done.

Adrenal insufficiency

Cortisol over 800 excludes a problem, normal response to Syncathen test (ACTH) at 1 hr should be over 470nmol/l (over 6yrs), 650 (under 6yrs).

Primary adrenal insufficiency – congenital adrenal hyperplasia (mostly 21OH deficiency), else autoimmune, genetic, infiltrative, adrenleukodystrophy (and exogenous steroid suppression).

Classic Addisonion picture – low sodium, high potassium, hyperpigmentation (can look slim and tanned, so misleadingly healthy!).

Physiological hydrocortisone replacement =10mg/m2/d in 3-4 divided doses.  Medication alert bracelet recommended, in case of crisis.  Monitor growth, BP.

If unwell, double HC dose (if varying doses, double highest dose) and give it three times daily. IM if necessary, +/- infusion.

Prolactin

Secreted from the pituitary, but also a stress hormone (can be used to distinguish pseudo seizures from epileptic seizures). So can go up to 1000 in healthy people. Always worth repeating a high result at least 24hrs hours later, after a 20 minute rest.

Important because of prolactinomas, which can cause:

  • gynaecomastia
  • galactorrhoea
  • delayed puberty
  • space occupying lesion effects – headaches, visual field defects

Any lesion in the vicinity of the pituitary may also cause raised prolactin so not specific.

In children, high levels can be due to presence of macroprotein isoforms, which are not considered pathological – lab can check.

Hypertension

In children under 10, high BP is usually secondary to an underlying disease or condition. Primary hypertension increasingly recognised in older, obese children.

Do repeated measurements, ideally automated home BP monitoring, before diagnosing hypertension. Check manually as well as with automated device. Beware “white coat effect”, even if not clearly anxious.

Use appropriate cuff size – cuff should cover at least 75% of the upper arm from the acromion to the olecranon (should be sufficient space at the antecubital fossa to apply stethoscope!) .  An inappropriately small cuff will overestimate BP.

Long list of causes, so follow the clues.

Family history important, of course.

Examination

So needs thorough history and examination, including:

  • Fundi
  • Bruits, radiofemoral delay
  • Neck for goitre

Complications

Consider then end organ effects –

  • Proteinuria, high creatinine
  • Retinopathy
  • Left ventricular hypertrophy, cardiac failure
  • Abnormal tone and reflexes, cranial nerve deficits if severe

Management

Depends on how high, whether other risk factors (diabetes, chronic kidney disease), symptoms and evidence of end organ damage.

Initially low salt diet, weight loss (if obese).  Remember other morbidities related to obesity.

Acute hypertension might need frusomide and/or nifedipine.

Long term treatment is only going to be started if no improvement with lifestyle measures. Target BP depends on risk factors, as above.

[2016 European Society for Hypertension guidelines]

Short Stature

Are they really? Plot height and weight, and check figures if in doubt!

Investigate if:

  • More than 2 standard deviations below mean worthy of investigation,
  • more than 2 standard deviations below mean parental height.
  • Height velocity less than 5cm per year

Is there evidence of chronic disease? Needs full history and examination, including urine dip. Common things would be renal failure, coeliac disease, IBD, hypothyroidism. Endocrine causes tend to produce relatively heavy children, other chronic diseases tend to produce relatively slight children.

Are they dysmorphic? Main syndromes to look out for:

  • Turners – besides short stature, webbed neck, characteristic facies, short metacarpals, broad chest with widely spaced nipples, hyperconvex fingernails and toenails (but can be missed); decreased growth velocity and delayed puberty

Bone age will be delayed in all except familial and idiopathic. Progressively falls behind in endocrine disorders.

Causes

Constitutional delay – good weight at birth, then “catch down” growth, dropping through centiles in infancy. Growth velocity is then normal, but with delayed bone age and delayed puberty.

Small for gestational age babies tend to catch up in first few years of life with their genetic potential, but can take up 4 years or more. 10% however remain small (more than 2 SDs below MPH) through life. Consider other causes if no catch up in first 6 months of life or still small at 2 years.

Growth hormone deficiency – can be congenital or acquired (head injury, meningitis etc). Early growth tends to be normal (growth hormone doesn’t contribute much in first few years of life). Look for microphallus and midline facial abnormalities.

Investigations

  • Karyotype if dysmorphic or if girl
  • TFTs
  • IGF1 – screening test for Growth hormone problems, but may need GH stimulation testing
  • U&Es, LFTs, CRP/ESR
  • Urinalysis
  • Bone age

Thyroid

Thyroid issues can be congenital, neonatal, autoimmune, or related to syndromes eg Downs, Digeorge.

Note that thyroid function tests can be affected by intercurrent illness, there is also viral thyroiditis where you might get transient (usually mild) abnormalities.  So borderline results (especially if asymptomatic or other medical issues) usually just need repeated.  If results confusing, do T3.  If normal then abnormal T4 likely to be transient.  If suspicion of evolving problem, do autoantibodies (TPO antibody, Thyroid Receptor Ab (TRab)).  If progressive decline then likely to be emerging autoimmune condition.

All kinds of unusual clinical presentations in thyroid disease, for example:

  • Effusions in hypothyroidism, including pericardial effusions – capillary dysfunction!? Impaired lymphatic drainage?
  • Body pain
  • Precocious puberty (although delayed more typical)

Congenital Hypothyroidism

Isolated TSH elevation >20 is usually treated.

True congenital hypothyroidism mostly dysgenesis, ie poorly formed gland, of which <2% have identified mutations (mostly thyroid peroxidise, thyroglobulin and TSH receptor proteins – EDTA sample, Dr Therese Bradley at SGH Genetics).  May be due to dyshormonogenesis (10%, autosomal dominant, gland looks normal on scan), TSH Receptor defect. Do a Family History.

Mostly found on newborn screening now.  Life long.

Placental thyroxine important, iodine too, on neonatal thyroid function.  In the first 14/7 of life, high TSH/T4/T3 seen.  Transient neonatal hypothyroidism seen, 25% of +ve guthrie tests!

Symptoms

If missed or untreated, classic signs are umbilical hernia, goitre, hoarse cry, coarse facies, Developmental Dysplasia of Hip!

Imaging

SPEG recommend that all families should be given the opportunity for imaging, subject to availability, because more informative than blood tests alone, will aid in genetic counselling, likelihood of lifelong treatment if proven permanent CH, provides a useful guide as to thyroxine dose.

Combined isotope and ultrasound imaging (dual scanning) is preferred. Isotope scans should be performed by day 5 of start of treatment to ensure avoidance of false negatives due to TSH suppression (advisable to take thyroid function sample on day of scans to confirm reliability of results). Ultrasound may show an abnormal gland (dyshormonogenesis) or else agenesis (no gland).   But in agenesis may be remnants of embryonic structural elements which can be mistaken for a gland – can persist into teenage years but max 5mm x 5mm!. Hence importance of supporting radio-isotope imaging.  Experience of ultrasonographer important.

Management

Some concern that thyroxine liquid not as consistent levels?  Automatic script request from pharmacy, patient then notified when ready.

Follow up

  1. Scottish guideline suggests typical doses at different ages, up to age 3, to encourage dose changes with growth rather than waiting till dose insufficient and hypothyroidism emerges (see table).  Use TFTs to confirm compliance.
  2. Assess growth: weight, length until 2 years, then height, head circumference until 3 years
  3. Assess development – consider pre-school audiology (for subtle hearing impairment due to CH)
  4. Transition – patient education. Boys to GP (unless problems with control), girls – to adult endocrinology (for pre-pregnancy counselling).

Aim for fT4 > 15 pmol/l and TSH <5.0 mU/l

Age LT4 dose (ug daily) LT4 dose (ug/kg/day)
Female Male Female Male
3 months 41.3 43.3 7.2 6.9
6 months 45.8 50.0 6.1 6.2
9 months 47.9 53.1 5.6 5.7
12 months 55.0 53.1 5.8 5.2
18 months 62.5 61.1 5.8 5.3
24 months 70.3 58.3 5.9 4.6
36 months 75.0 62.5 5.3 4.25