The aim of the present study is to evaluate the prognostic value of intra-operative indocyanine staining scoring concerning 24 hours post-operative PTH levels and the possible advantages that its' use can give in terms of clinical practice compared to conventionally operated patients.

Study objectives are:

• Detecting the changes of practice in performing total thyroidectomy with ICG.
• Comparing ICG-performed minimal invasive total thyroidectomy
• Identifying the cut-off points that predict low PTH levels (less than 20pg/ml)
• Identifying and analyzing problematic groups of patients The study is designed as a prospective observational multi-center study. Any patient that has indication for a total thyroidectomy will be considered eligible.

The study will be conducted until 60 subjects are included. It is estimated that it will take up to 3 months to enroll the patients.

Pre-Surgery: Procedures preformed such as routine hospital examinations, antibiotic prophylactic treatment, anticoagulant treatment and diet will be according to the standard management protocol and will be recorded for the study. The following pre-surgery information will be recorded:

1. Demographic information including: name, age, gender, ethnicity
2. Height, weight, BMI and American Society of Anesthesiologists physical status classification system (I-VI)
3. Behavioral history (Smoking, alcohol or drug use)
4. Preoperative labs (WBC, Ht, Hgb, Ca2+, P, fT3, fT4, TSH, PTH, VitD)
5. Diagnosis including clinical observations and previous imaging results
6. Pre-operative characteristics of the adenoma
7. Medications
8. Current and past history of surgical and medical comorbidities

Intra-operative: The surgeon will perform the preplanned operation. The following intraoperative variables will be recorded for all patients:

1. Surgery date
2. Duration of surgery
3. Operation performed
4. Procedure related comments
5. Number and location of the visualized glands
6. Intra-operative ICG score (ranging from 1 to 3 [5]) for each grand

Pathology data form: The following pathology data will be recorded for all patients:

1. Post-operative diagnosis including pathology report
2. Possible parathyroids excised Postoperative follow-up: Follow-up evaluation will be performed during hospitalization

1 Postoperative labs (WBC, Ht, Hgb, Ca2+, P, fT3, fT4, TSH, PTH)

Inclusion Criteria:

• Patient is over 18 years old
• Patient scheduled for a non-emergency operation
• Patient eligible for total thyroidectomy

Exclusion Criteria:

• Patient is participating in another clinical trial which may affect this study's outcomes
• Prior operation in the neck
• Primary or secondary hyperparathyroidism
• Vitamin D deficiency
• Use of drugs that influences calcium metabolism (Vitamin D analogues, oral calcium supplements, bisphosphonates, teriparatide, thiazide diuretics, aromatase inhibitors)

All patients that are going to have a total thyroidectomy regardless of the underlying pathology