diagnosis?

Patient M.S. 23/F came in with palpable nodule on the anterior left side of the neck.

Seven months prior to consultation (January), patient noted her weight to be around 55kg. Three months later (April), she noticed a decrease in weight, dropping down to 47kg. Patient denies any change in normal eating habits nor daily routines. She also denies experiencing any acute disease nor depression during the time. Following the  unexplained weight loss , patient started complaining of easy fatigability, anorexia, palpitations and mild tremors. 

A month prior to consult (June 15), patient had a thyroid function test and an ultrasound done. The result are as follows:

Thyroid function test

FT3 =  6.54 pmol/L (4.0 - 8.3)
FT4 = 12.91 pmo/L (9.0 - 20.0)

TSH = < 0

Thyroid ultrasound

R lobe: 3.98 x 1.09 x 1.15

L lobe: 4.55 x 1.54 x 1.62

Both lobes are slightly enlarged showing multiple hypoechoic solid masses measuring about 0.55 x 1.13cms and 0.88 x 1.06cms (right) and 1.08 x 1.49cms and 1.15 x 1.44cms (left.
Isthmus and adjacent vascular structures are unremarkable.

Two weeks later (June 28), a repeat thyroid function test was done. the result are as follows:

Thyroid function test

FT3 =  4.72 pg/mL (1.71 - 3.71)
FT4 = 1.33 pg/dL (0.70 - 1.48)

Three days prior to consult (July 9), a thyroid scan with radioactive iodine uptake was done. Result are as follows:

Thyroid scan

Radiotracer distribution is homogenous with decreased tracer uptake in the superior and inferior portions of the right lobe and in the medial and lateral portions of the left lobe.

Thyroid uptake of iodine-131 at 2hrs is 8.2% (5 - 15%) and at 24hrs is 30.2 (20 - 45%).

Interpretation: Nonhyperactive goiter with probable cold nodules and/or fibrosis in the superior and inferior of the right lobe and in the medial and lateral portions of the left lobe.

Diagnosis?