Thyroid Lab Questions

Question 1

A Patient with apparent symptoms of hypothyroidism. what labratory test would be the most appropriate to preform?

Symptomes of Hypothyroidism:

• Fatigue, Cold, Constipation, Weight gain.
• Myxedema - TSH↑ causes fibroblasts to deposit more GAGs (Hyluronic acid) - Osmotic edema
• Hoarse voice, Ascites, Pleural, Pericardial effusion

Answer 1

Check for TSH level - High/Normal/low

• If TSH High+T3 Low: Primary Hypothyroidism: Check for Anti-TPO/TG - Mostly in Hashimoto or Anti-TSH-R mostly in Graves.
• If TSH low+T3 low: Secondary Hypothyroidism: If administration of TRH doesnt help it is confirmed
• If administer of TRH helps - Tertiary Hypothyroidism

Question 2

A 40 year old woman seeks evaluation for subfebrility and diarrhea commenced 2–3 weeks before. Blood glucose: 6.6 mmol/l. Blood pressure: 160/85 mmHg, heart rate: 120/min. Serum TSH: 0.15 mU/l (decreased), FT4: 60 pmol/l (elevated), TRAb titer elevated, TPO-antibody positive. What is the most likely diagnosis? What other test would you order to specify your diagnosis?

Answer 2

This is most likely Graves: Low TSH (“Supersensitive”)

• Symtomes: Temp↑,BP↑,Diaherria
• Labs:Glucose↑, FT4↑, TRAb↑, Anti-TPO+

Further Tests: Structure and Function of Nodules

• US: Solid Nodes distinguished from Cystic Nodes
• Scintigraphy: Administation of Radioactive I / Tc - Taken up by Thyroid - “diffuse warmth” = Grave’s / “Focused” = Adenoms / “Cold” = Malignancy chance↑ - Fine needle cytology to confrim.

Question 3

A 42 year old woman developed diffusely enlarged, painless thyroid glands. Total T4 is decreased, thyroid uptake of radioiodine is low. ECG reveals low voltage and
bradycardia. The thyroid autoimmunity panel demonstrates the presence of TgAb and TPO-Ab. What is the most likely diagnosis? Is this condition characterized by a hypo or hyperfunction of the thyroid gland?

Answer 3

Probably Hashimoto : T4↓ with Anti-TPO+ and Ant-TG+

• Painless goiter can also be: I2 def. , Congenital enzyme abnormalities or Neoplasm
• Low voltage = Pericardial Myxedema
• HR↓ because of T3↓
• Low radioiodine uptake = Inflammaotry damage / NIS Problems

Hashimoto initially can present with Hyperthyroid (lysis) and eventual hypothyroidism it is Anti-TSH-R Negative.

Question 4

A schoolgirl at the age of 14 without any complaints develops diffusely enlarged painless thyroid glands recognized accidentally by the school doctor. Laboratory findings: FT4 is slightly decreased, whereas total T3 is slightly elevated. Thyroid uptake of radioiodine is increased. FT4 gets normalized after treatment with anorganic iodine. What is the most likely diagnosis? Try to interpret the opposite changes in hormone levels.

Answer 4

• Iodine treatment responsivness = Iodine deficiency
• Endemic Goiter: in areas where the soil (thus food and water) is short on Iodine. usual onset is in pregnancy or puberty.
• High radioiodine uptake: NIS was upregulated by low plasma iodide and High TSH.
• because T4 needs 4 iodines wheras T3 needs 3 and also it is more potent - there is a preferential higher synthesis of T3 in case of iodine deficiency!

Question 5

An 11 month old baby with protruded belly and retarded in movement development has been brought for medical evaluation. Serum FT4 and FT3 are decreased. Serum MIT/DIT are elevated and their urinary excretion increased. What is the most likely diagnosis?

Answer 5

Cretinism - mental and physical development halted by congenital thyroid hormone deficiency.

• Likely TPO deficiency: MIT/DIT↑ and T3/T4↓ - No sufficient Iodination of Thyriod hormone precursers.
• Others deficiencies are in TSHR/TG/Deiodinase
• Perchlorate Test: Competitive inhibitor of thyroid iodine uptake, shows in a scintography for activity of the TPO with radiolabled iodine. Stable warmth after perchlorate means TPO oxidases and incorporates Iodine sufficiently!

Question 6

List those thyroid tests that are considered helpful in the diagnosis of thyroid cancer!

General Clinical Image:

• Risk: Older female= more bengin while Younger males = more Malignant
• Nodules Palpation: Malignant are hard and Bengin are soft

Answer 6

US Nodes: Solid/Hollow/Fluid filled cysts + Scintography

• “Cold” Nodes: No Iodine uptake and Hormone synthesis - If Hollow =Cysts If Solid = Malignant.
• “Warm” Nodes: Good Hormone Synthesis If Solid normally these are Adenomas.
• “Hot” Nodes: Focal areas of High synthetic activity lowring TSH may by Toxic Adenoma: Thyrotoxicosis

Thyroglobulin in Plasma=Neoplasm/Thyroditis

Fine Needle Biopsy of nodes

CEA and Calcitonin: markers in medulla carcinoma