medicalrojak

Anatomy of thyroid

• Landmarks: laryngeal prominence (adam’s apple) of thyroid cartilage and cricoid cartilage which lies below it
• Isthmus of thyroid normally lies just below the cricoid cartilage
• High vs low lying thyroid
  – If distance between laryngeal prominence and the suprasternal notch is far (eg 10cm), the thyroid gland maybe high lying (pseudogoiter)
  – If laryngeal prominence is close to suprasternal notch (<5cm), the thyroid gland is low lying (and located retrosternally). Palpation maybe impossible.

Inspection of thyroid gland

• See from the side. The line between cricoid prominence and suprasternal notch (where the thyroid gland is located) is a straight line.
• If it is bowed, consider goiter

Palpation

• An easier way to palpate thyroid gland

What do we palpate?

• Size
• Consistency (hard or soft)
• Nodular
• Tenderness

The key to know that what we palpate is thyroid gland is

• It moves during swallowing, and then hesitate a while before returning. As thyroid gland and tracheal is connected by ligaments.
• If it does not move during sallowing or does not hesitate before returning to its original position, it is likely not thyroid gland.

Cervical goiter

Estimation of size

• Rule of thumb: lateral lobe is enlarged if it is larger than distal phalanx of the patient’s thumb
• WHO grading
  

Retrosternal goiter

• May cause TOS, SVC syndrome and compression of trachea and esophagus
• TOS (thoracic outlet syndrome):
  – Compression of brachial plexus: pain in the multiple myotomes in UE
  – Compression of subclavian vein: UE venous thrombosis (Paget-Schroetter syndrome)
• SVC syndrome:  elevated JVP + plethora + facial & arm edema
• Compression of trachea and esophagus: dyspnea, stridor, dysphagia

Thyroglossal cyst

• Cystic swellings of thyroglossal duct , an epithelium lined remnant marking the descent of thyroid tissue from the base of tongue to its final location
• Midline neck mass
• Characteristic sign is upward movement when the patient protrudes the tongue

Delphian node

• Prelaryngeal lymph node
• Named Delphian because it is the first one exposed during surgery and its appearance often foretells what the surgeon will find in thyroid.
• Radiologically, it is situated in lymph node level VI
• If it’s palpable, it is usually enlarged – suspect malignancy or Hashimoto’s thyroidits
  

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Hypothyroidism

• Classical triad of puffy skin + delayed reflexes + thick & nasal speech
• Features
  – Skin: dry, cold, puffy skin
  – Achlles reflex: delayed reflex due to prolonged contraction & relaxation
  – Hypothyroid speech: slow, deep and nasal (as if patient has a cold)
• Billewicz Diagnostic Index for hypothyroidism
  >30 has a high likelihood of hypothyroidism
  

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Graves disease

• Triad of prominent eyes + goiter + tachycardia
• Auscultation in thyroid gland can often ellicit bruit (in 70% of patents)
• Eye findings:
  Lid lag: von Graefe sign
  – ask patient to look down, the upper eyelid “lags” behind

  Lid retraction: Dalrymple’s sign
  – ask patient to look straight, white sclera is seen between the limbus and the lid margin; usually the lid margin rests just below the corneal limbus

  Graves opthalmopathy
  –  NO SPECS
  – Consider if patient with Graves disease complain of gritty sensation in the eyes or diplopia
  

• CV findings:
  – Loud S1
  – Tachycardia
  – Means Lerman scratch (systolic rub resembling scratching near the left 2nd ICS)
• Skin findings:
  – Moist (due to increased sweating) and warm
  – Pretibial myxoedema
• Neuromuscular findings
  – Fatigue & weakness
  – Fine tremor due to sympathetic overflow
  – Brisk ankle reflexes

** Other ddx of lid retraction

• Facial palsy: unilateral weakness of orbicularis oculi –> levator palpebrae is no longer being opposed
  
• Unilateral ptosis: attempts to elevate the weakened lid causes excessive neural signals which end up elevating another lid
• Previous eyelid surgeru

More eponyms?

Von Graefe: lid lag (We look down in Grief !)

Darylrmple sign: lid retraction (DaryLRmple)

Joffroy sign: lack of forehead wrinkling (FF resembling wrinkling)

Stellwag sign: staring look (Stellwag for Staring)

Moebius sign: Poor convergence (Merging Of EyeBalls Is UnSuccessful)

Wayne Diagnostic Index for hyperthyroidism >20 points have a high likelihood for hyperthyroidism

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Note: BOTH hypo and hyperthyroidism cause amenorrhea !

• Hypothyroidism: increased TRH causes increased prolactin production which blocks GnRH
• Hyperthyroidis: multiple mechanisms, but likely linked to high SHBG which leads to high ratio of bound estradiol. Only free estradiol can induce a LH peak.
  

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Mnemonic for THYROID disorders: NEVER FORGET THEM AGAIN !

THYROIDISM

• Tremor (in hyper)
• Heart Rate
• Yawn (fatigue in both)
• Reflexes (brisk or delayed)
• Oligomenorrhea
• Intolerance to temperature  (heat or cold)
• Diarrhea (or constipation)
• Increased or decreased appetitie
• Skin (cool,dry and puffy or moist and warm skin)
• Myxoedema (facial puffiness in hypothyroidism, pretibial myxoedema)

Reference:

Steven McGee. Evidence Based Physical Diagnosis. Pg 250-276