Transcript Thyroid function Tests

Thyroid: Clinical Cases
Dr Sunil Zachariah
Consultant Endocrinologist
Surrey and Sussex NHS Trust
& Spire Gatwick Park Hospital


Thyroid is the only source of T4
Thyroid secretes 20% of T3, remainder
is generated in extra glandular tissues
by conversion of T4 to T3
Normal range



FT4
fT3
TSH
11.5-23 pmol/l
3-6.7 pmol/l
0.3-5.5 mu/L
Case 1





Female aged 40 years
Palpitations, weight loss and mild
proptosis
Smallish smooth goitre
FT4 80
TSH<0.01
Graves Disease






TSH receptor
antibodies
Carbimazole
Propylthiouracil
Treatment schedule
?Block and replace
Permanent cure
Case 2





Female aged 76 years
Gradual weight loss
Solitary thyroid nodule
FT4 32
TSH<0.01
Management toxic Nodule


Radioactive iodine
?FNA first if palpable nodule as low risk
of malignancy in toxic nodule
Case 3




60 year old female
6 weeks post radioiodine treatment
FT4 11
TSH 0.02
Post radioiodine thyroid function



Check 6 weeks after treatment
TFTs may fluctuate
50% risk of hypothyroidism
Case 4



Female aged 79 years with fast AF
FT4 19.5
TSH 0.2




This case probably not for antithyroid
treatment
If overtly hyperthyroid treat
Subclinical hyperthyroidism: Normal
FT4, Low TSH
Risk factor for Atrial fibrillation,
osteoporosis
Case 5






50 year old man
Ventricular tachycardia with poor LV
function
Controlled on Amiodarone
FT4 50
FT3 7
TSH<0.01
Amiodarone and Thyroid




Inhibits thyroidal iodide uptake
Inhibits conversion of T4 to T3
intracellularly
Inhibits T4 entry into cells
Direct T3 antagonism at level of cardiac
tissue
What does it do to TFTs?



Early[1-10 days]: TSH increase, FT3
decrease, then Ft4 increase after 4 days
Later[1-4 months]: Ft4 increase by
40%, FT3 remains low or normal, TSH
levels normalise
Long term: TSH may suppress
Amiodarone induced hyperthyroidism





2-12%
Type 1: Iodine overload in abnormal gland,
treat with carbimazole or lithium
Type 2: Glandular damage, release of
preformed hormones, treat with prednisolone
0.5-1.25 mg/kg for 3-6 weeks
Management of tachyarrhythmia's: beta
blockers if not in CCF
?total thyroidectomy (not radioiodine)
Case 6





30 year old female
Recent flu
tender enlargement thyroid
FT4 28
TSH<0.01
De Quervains thyroiditis





Recheck TFTs-probably hypothyroid by
then
Thyroid antibodies and ESR
Thyroid scintigram-reduced uptake
Symptomatic treatment with NSAIDs
Warn the possibility of recurrence
Case 7






Female age 25 years
Hyperpyrexia
ITU admission
Profound muscle weakness requiring
ventilation
FT4 210
TSH<0.01
Thyrotoxic crisis



Carbimazole 60-100 mg via NG tube
Propranolol infusion
Profound myopathy and even
neuropathy can be associated with
Grave’s
Case 8





65 year old male
Pre coronary artery bypass surgery
Routine blood tests
FT4 3 mU/L
TSH 40 pmol/L
Management hypothyroidism with Coronary
artery disease


May need to put in stents to allow
introduction of triodothyronine and then
thyroxine
Some patients symptomatic when
thyroxine started/increased
Case 9




Female aged 32 years
Weight gain and thyroid
FT4 13
TSH 5.5
Sub clinical hypothyroidism





TSH>10
Antibody positive
Family history
Symptomatic
Monitor TFT 6 monthly
Case 10



Hypothyroid on replacement thyroxine
300 mcg
FT4 23
TSH 15
Hypothyroidism requiring high dose
replacement



Check tablets each visit-check
compliance
Check for malabsorption but unlikely
Probably continue to see but at
infrequent intervals
Case 11






Female aged 60 years
Found collapsed at home
History of epilepsy
TFT checked in Causality
FT4 8.5
TSH 4.0
Low FT4, normal TSH



Sick euthyroid
Possibly hypopituitary-cortisol/FSH/LH
Check medication-can be secondary to
carbamazepine
Sick Euthyroid syndrome




Non thyroidal illness syndrome
Low FT4 and T3
Inappropriately normal/suppressed TSH
Context: Starvation, ITU, severe
infections, renal failure, cardiac failure,
malignancy
Case 13
Female aged 34 years
 Secondary amenorrhoea
 Low TSH
 Low FT4
Hypopituitarism



FSH/LH/Prolactin/cortisol
MRI Pitutary; ?empty fossa ?large
adenoma
Start hydrocortisone first if needed,
before thyroxine replacement
Case 14





22 year old female
Admitted with hyper emesis gravidarum
Pulse 110 bpm
FT4 29
TSH<0.01
Management


Usually HCG induced in which case it
will resolve spontaneously by around 14
weeks
If positive thyroid antibodies or history
of grave’s disease then treat with PTU
Case 14






A] Palpitations, 10 weeks post partum
Ft4 32
TSH 0.2
B] Tired, 10 weeks post partum
FT4 9
TSH 8
POSTPARTUM THYROIDITIS


Incidence varies from 5-11%
More common in women with a family
history of hypothyroidism and positive
TPO antibodies
CLINICAL FEATURES



Presentation is usually 3-4 months
postpartum
Can be hypothyroidism (40%),
hyperthyroidism (40%) or
biphasic(20%)
Goiter is present in 50% of patients
Pathogenesis


Destructive autoimmune thyroiditis
causing first release of thyroxine and
then hypothyroidism as the thyroid
reserve is depleted
FNAC shows lymphocytic thyroiditis
Diagnosis


Advise routine TFT in females who have
positive TPO antibodies and type 1
diabetes
To distinguish from Graves disease use
thyroid isotope scan and TSH receptor
Ab
Management





Most patients recover spontaneously without
requiring treatment
If hyperthyroid use beta blockers rather than
antithyroid drugs as the problem is increased
release, not synthesis
Hypothyroid phase is more likely to require
treatment
Only 3-4% remain permanently hypothyroid
10-25% will recur in future pregnancies
Case 15


Female aged 30 years
New Thyroid enlargement
New Thyroid swelling



FNAC if nodule size>1 cm
Repeat FNAC in 6 months
Impossible to differentiate between
benign and malignant follicular
neoplasm using FNAC
Case 16



Long standing goitre
FT4 28
TSH 7
Measurable TSH with raised FT4



Heterophile antibodies
TSH resistance syndromes
TSH oma-very rare
Thyroid hormone resistance



Syndrome characterized by reduced
responsiveness to elevated circulating
FT4 and FT3, non suppressed TSH
Short stature, hyperactivity, attention
deficit
Differential diagnosis includes TSH
secreting pituitary tumour
Case 17






27 year old female
Follicular Cancer of Thyroid
Post surgery, post radioiodine ablation
On Thyroxine replacement (175 mcg)
FT4 19.8
TSH 0.05
Follow up of thyroid Cancer



Original diagnosis and treatment
If total thyroidectomy and ablative
radioiodine, thyroglobulins usually
undetectable if TSH unrecordable
Maintain TSH<0.05