Question

State a clinical diagnosis for the results of the laboratory assays/tests below and describe the relevant sonographic findings of each condition.

i. ↑Ca2+, ↑PTH

ii. FT4/FT3↓, TSH↑

iii. FT4/FT3↑, TSH↓

Answer 1

1) Increase in calcium and PTH (para thyroid hormone)

There are four parathyroid glands located on the back side of the thyroid gland.

The parathyroid glands secrete a hormone called parathyroid hormone.

The secretion of PTH is controlled by the levels of calcium in the circulatory fluids.

This hormone increases the calcium levels in the blood. Thus, it is a hypercalcemic hormone.

It stimulates the process of bone reabsorption by stimulating the osteoclasts to dissolve calcium phosphate of the matrix of bones releasing calcium into the blood, which is known as hypercalcemia.

It also stimulates reabsorption of calcium ions by renal tubules and increases the absorption of calcium from the gut.

CLINICAL DIAGNOSIS - hyper parathyroidism - due to hypertrophy of parathyroid gland, which causes increase in PTH levels, in turn, it increases calcium levels in the blood.

Ultrasonic findings - Enalrged gland and hypoechoic lesions.

2) FT4/FT3 decreases and FSH increases

Thyroid gland secretes thyroid hormones namely - thyroxine (T4) and tri-iodo-thyronine (T3).

Thyroid hormone secretion is controlled by thyroid stimulating hormone (TSH).

Hypothalamus secretes thyrotrophin releasing hormone (TRH), it is transported to the median eminence, where it is stored. From there, TSH is released into the hypothalamo-hypophysial portal vessels to stimulate the secretion of TSH by the thyrptrophs cells of the anterior pituitary gland. TRH acts on the anterior pituitary gland to release TSH.

TSH stimulates the production of thyroid hormones.

Control of TSH secretion -

Fall in thyroid hormones - T3 and T4 via negative feedback mechanism stimulates TSH secretion to causes rise in free T4 and T3 levels.

CLINICAL DIAGNOSIS - Hypothyroidism

Ultrasonic findings - Gland show enlarged or normal or small and hypoechogenicity.

Hypothyroidism is the condition resulting from reduced circulating levels of free T3 and T4.

Due to low T3 and T4 levels, anterior pituitary gland releases TSH to stimulate the production of T3 and T4.

So, in hypothyroidism- T3 and T4 decreases and TSH increases.

3) FT4/FT3 increases and TSH decreases

Rise in free T3 and T4 levels via negative feedback mechanism inhibits TSH secretion and causes fall in free T4 and T3 levels.

CLINICAL DIAGNOSIS - Hyperthyroidism

Ultrasonic findings - enlarged gland, heterogeneous echo texture and increased vascularity.

Hyperthyroidism is the condition resulting from increases circulating levels in free T4 and T3 levels.

As T4 and T3 levels are increased, TSH secretion from anterior pituitary gland decreased to decrease the T3 and T4 levels.

So,T4 and T3 levels are increased and TSH decreased.