Initiating prophylactic oral elemental calcium, the first day after surgery can reduce the incidence of postoperative hypocalcemia, the length of hospital stay and the need for parenteral calcium. The prescription of vitamina D VD is also recommended. Conclusion : Hypocalcemia secondary to hypoparathyroidism, is a frequent complication after thyroidectomy.
Early diagnosis by assessing predictive factors can prevent hypocalcemia and decrease mobility and mortality. Early evaluation of iPTH and corrected serum calcium CSC after neck surgery, are the most appropriate tests to diagnose transitory and permanent hypoparathyroidism.
Hypocalcemia is a frequent complication in patients undergoing thyroid surgery. It increases the hospitalized time and costs, decreasing the quality of life and the risk of death. Recommendations are given for the prevention, diagnosis and treatment of hypoparathyroidism in patients undergoing total thyroidectomy. Hypocalcemia is one of the major complications of surgical interventions in the central neck level VI due to the small size of the parathyroid glands PGs , their proximity and firm adherence to the thyroid, and the risk of compromising their blood flow during surgery.
Some efforts have been made to find, intra and postoperative hypocalcemia predictors in an attempt to prevent and manage it early. Nevertheless, lack algorithms for its prevention, diagnosis and treatment. These algorithms could reduce the number of post-operative admissions to the emergency room, and improve morbidity.
We present a review of the literature on the prevention and early detection of post-surgical hypocalcemia; and also give some recommendations for the acute management of the patients undergoing thyroidectomy. Anatomy and Physiology of the parathyroid glands: The PGs are small glands, brown colored, derived from the pharyngeal pouches and usually located on the dorsal side of the upper and lower poles of the thyroid gland.
Given its embryonic origin, they may be located anywhere along the migration route of the pharyngeal pouches carotid sheath, thymus or anywhere in the anterior mediastinum.
Irrigation to the superior upper parathyroid glands often depends on the superior thyroid artery STA , and in some cases from a branch of the anastomosis between the upper and lower thyroid arteries [3]. The inferior PGs irrigation is predominantly given by branches of the inferior thyroid artery, and, less frequently by branches of the STA, depending on its location when located in the thyrothymic ligament there is no additional supply by the STA.
In a few cases the irrigation comes from branches of the internal mammary artery []. PGs through the production of parathyroid hormone PTH play an indispensable role regulating serum calcium, increasing the calcium levels in blood by increasing renal reabsorption of calcium, bone resorption and activation of calcidiol to stimulate intestinal calcium absorption; all this by means of PTH receptors coupled to G proteins present in these tissues [7,8].
Thus, any injury to the PGs leading to the reduction or loss of their function will generate a reduction in serum calcium which, when severe, can be life threatening, or in a lesser extent, affect importantly the quality of life of the patients and increase the days of in hospital care [9,10]. Transient hypoparathyroidism is defined as the resolution of hypocalcemia, without treatment after the first months post-surgery [9,11,12,24,26,28].
Signs and symptoms of hypocalcemia depend on the severity and the acuity of the onset. In acute hypocalcemia the first symptoms described are neurological; with paresthesias in the perioral region, hands and feet and if untreated progressing to cramps, hyperreflexia and muscle spasms. Irritability, depression and psychotic symptoms may be associated findings.
In severe cases, angina pectoris, congestive heart failure or syncope, due to changes in contractility or cardiac electrical conduction may occur. Laryngospasm, bronchospasm or epileptic crises can also occur all of which compromising the patient's life [36,37]. It consists on the spasm of the hand and forearm due to the occlusion of the brachial artery when a blood pressure cuff is placed on the arm and inflated to 10 mm Hg above the systolic pressure during at least 2 minutes.
The most frequent electrocardiographic findings are QTc and ST segments prolongation, T wave inversion and in severe cases, AV block or ventricular fibrillation [22,38]. In chronic hypocalcemia symptoms such as dry skin, rough hair or fragile nails are often more subtle. In spite of that, severe complications may appear in chronic cases such as papilledema, parkinsonism, subcapsular cataracts, calcification of the basal ganglia and intracerebral hemorrhages [22,38].
Other lab tests are important in the evaluation of the patient suspected with this condition: [9,10,22,33,38]. Serum iPTH levels take before, during and after thyroidectomy have been evaluated in different studies as a predictive factor for mild to severe post-surgical hypocalcemia and post-surgical hypoparathyroidism.
The decrease of the postoperative iPTH value compared with the preoperative, has been proven as a predicting factor of transient and permanent hypocalcemia [11,20,31]. Different values of iPTH defined as threshold taken at different latency times which can be as early as 5 minutes after thyroidectomy intraoperative iPTH , in the first post-surgical hour peri-operative iPTH or at 24 hours post-surgical post-operative iPTH , have been reported.
Prevention of postsurgical hypoparathyroidism: As previously described, the insufficiency or deficiency of VD is an independent preoperative predictor Figure 1 , contributing to postsurgical hypocalcemia. Its measurement is suggested routinely as a first step in preventing post-operative hipocalcemia [30,31]. The high cost is decreasing progressively, and its benefit supports its routine use. Figure 2.
Approach to the acute patient with hypocalcaemia after thyroid surgery. It is recommended to follow up and educational interventions to promote a healthy lifestyle with appropriate diet; improve adherence, and the proper use of drug therapy.
It is a known fact to every surgeon that in order to prevent postoperative hypoparathyroidism while performing thyroid surgeries, the best effort must be made to avoid any kind of damage, either directly to the glands or to the blood supply of the parathyroids. A thorough knowledge of the anatomy and the most frequent variations of the location and blood supply to the glands on the part of the experienced thyroid surgeon is the best tool in preventing damage to the parathyroids and their function [55].
Identifying the location of the PGs and their major vessels particularly the inferior thyroid artery and its usual bifurcation, its relation to the RLN and its distal branches and trying to ligate them as distally as possible are the mainstay of a proper surgical technique.
Also, a plane of cold capsular dissection, and the use of ultrasound rather than mono or bipolar energy when needed, aid in the objective of preventing vascular compromise to the glands. Nevertheless, even when the surgeon is confident that the PGs are intact and viable at the completion of the procedure, hypocalcaemia may occur. The mechanism of hypoparathyroidism after thyroidectomy is not entirely understood, but the manipulation of the PGs producing transient parathyroid insufficiency or reversible ischemia is commonly cited [56,57].
Based in the findings described above, many groups have developed protocols that include perioperative iPTH and calcium serum levels in order to classify their patients within risk groups and allowing either an early discharge or the establishing of an early in-hospital treatment for thyroidectomized patients using calcium supplements and adjusting surveillance. This has reduced emergency room readmissions as well as prolonged unjustified hospitalizations, improving the quality of life and therefore reducing costs.
Since there are different values in the protocols and articles reported, we present an algorithm based on the literature, adjusted to what is most frequently observed and recommended at our institutions. Prophylactic supplementation of oral calcium from day 1 postoperative reduces the incidence of postoperative symptomatic hypocalcemia, length of hospital stays and the need for using parenteral calcium in the different schemes [58,59].
Once normalized, weekly monitoring of CSC for albumin and phosphorus and titrating doses according to the reports is the generalized use [14,18,57]. Detection, diagnosis and management of hypoparathyrodism : To assess the presence of hypoparathyroidism, the levels of iPTH, serum total calcium and albumin should be measured during the first 24 hours after surgery and the patients should be classified into 3 groups:.
If the patient shows a CSC between 7. High risk patient: If the values of CSC are below 7. If CSC levels is persistently below 7. EKG monitoring must be done during calcium infusion. It is also recommended to give vitamin D additional to calcium when the patient does not take vitamin D cholecalciferol supplements. Outpatient management of hypoparathyroidism : Patients who fail to show normal levels of CSC and symptoms of hypocalcemia persist can be used diuretic type thiazides if blood pressure is normal or elevated.
Thiazide diuretics lower urine calcium excretion because they enhance renal calcium reabsorption, at the distal tubule [62]. This inhibits NaCl resorption, promoting its excretion and decreasing the effective volume. The hypocalciuric effect of thiazides is not just secondary to the effective volume depletion but depends upon the levels of PTH near normal circulating hormone and producing hypercalcemia due to the calcium release from the bone and probably increasing PTH action in the bone and kidney [64,65].
May need repeat doses or more aggressive replacement dependent on the severity of the hypomagnesemia. Shoback, D. N Engl J Med. Endocr J. J Bone Miner Res. Khan, A, Fong, J. Can Fam Physician. J Clin Endocrinol Metab. All rights reserved. No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. Show More. Login Register. Enjoying our content? Thanks for visiting Endocrinology Advisor.
If you wish to read unlimited content, please log in or register below. Registration is free. Register for free and gain unlimited access to:. Hypocalcemia I. Continue Reading. Jump to Section I. Diagnostic Approach A. What is the differential diagnosis for this problem? Most common Less common B. References 1.
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