Postoperative Tetany Research Articles

Evaluation of Hypoparathyroidism following Total Thyroidectomy

The most common cause of hypoparathyroidism is damage to the glands during thyroid surgery. Parathyroid gland preservation during thyroidectomy is not only desirable, but essential for the effective management of surgical diseases of the thyroid gland
 Objective: To find out the incidence rate of hypoparathyroidism after total thyroidectomy.
 Methods: Study Period: 2 years from Jan 2017 to December 2018
 Place of Study : National Institute of ENT, Tejgaon, Dhaka
 Study Design: Prospective Observational Study
 Sample size: 107
 Sampling Technique: Convenient Sampling technique
 Results: Among the 107 cases 39 cases were malignant comprising 36.45% of the cases. toxic multinodular goitre were 6 cases among 107 cases (5.6%) and rest 62 cases were benign multinodular goitre with or without cystic change and follicular adenomas (57.94 %). 29 cases out of 39 malignant cases were papillary carcinoma of thyroid (74.36% of malignant lesions), 2 cases of medullary Ca thyroid (5.12 % of malignant lesions) rest 8 were follicular carcinoma (20.51% of malignant lesions). 26 out of 107 (24.30%) cases suffered from postoperative hypocalcaemic tetany within 1st-5th POD. Their parathyroid hormones were significantly reduced and serum calcium were also reduced and they required calcium supplementation. In 5 (4.67%) cases there was no sign and symptoms of tetany but their serum parathormone levels were little below normal level but serum calcium levels were normal and therefore no calcium supplementation were given. The rest 76 (71.03%) cases did not show any sign or symptoms of tetany and did not require calcium supplementation. Among the patients who suffered from tetany majority were cases of Carcinoma of thyroid (18 out of 26 patients of hypoparathyroidism) 69.23%, however lateral neck dissection did not seem to affect decline in parathyroid function as 10 out of 18 patients with thyroid malignancy who suffered from postoperative tetany undergone level II to level V neck dissection in addition to total thyroidectomy.
 Bangladesh J Otorhinolaryngol; October 2020; 26(2): 116-120

The Preservation and Autotransplantation of the Parathyroid Glands in Total Thyroidectomy in Patients With Thyroid Cancer—A Strategy for Avoiding Permanent Hypoparathyroidism

Hypoparathyroidism is a complication that occurs after total thyroidectomy (TT) in patients with thyroid cancer. We tried to determine a strategy for avoiding permanent hypoparathyroidism. A total of 42 patients underwent TT for thyroid cancer between April 2009 and March 2014. One or more parathyroid glands (PGs) could be macroscopically preserved in all of the patients. First, we evaluated the association between the number of PGs that were macroscopically preserved and the postoperative course in 28 patients without autotransplantation. The number of preserved PGs was not associated with postoperative tetany or the serum levels of calcium or phosphorous on postoperative day 1, or the proportion of patients who needed to take calcium supplements or a vitamin D analog. However, only the patients with a single preserved PG required calcium supplementation for longer than 1 year (33.3%, P < 0.05). Next, we compared the clinical course with PG autotransplantation in 16 patients in whom a single PG was preserved. Although the result was not statistically significant, only the patients without autotransplantation required calcium supplementation for longer than 1 year. To avoid permanent hypoparathyroidism after TT, it should be essential to preserve at least 2 PGs or to preserve 1 PG and perform autotransplantation.

Postoperative Hypocalcemia After Thyroidectomy for Graves' Disease

It is believed that patients who undergo thyroidectomy for Graves' disease are more likely to experience postoperative hypocalcemia than patients undergoing total thyroidectomy for other indications. However, no study has directly compared these two groups of patients. The aim of this study was to determine whether there was an increased incidence or severity of postoperative hypocalcemia in patients who underwent thyroidectomy for Graves' disease. An institutional review board-approved database was created of all patients who underwent thyroidectomy from 1998 to 2009 at the Johns Hopkins Hospital. There were a total of 68 patients with Graves' disease who underwent surgery. Fifty-five patients who underwent total thyroidectomy were randomly selected and served as control subjects. An analysis was conducted that examined potential covariates for postoperative hypocalcemia, including age, gender, ethnicity, preoperative alkaline phosphatase level, size of goiter, whether parathyroid tissue or glands were present in the specimen, and the reason the patient underwent surgery. Specific outcomes examined were calcium levels on postoperative day 1, whether or not patients experienced symptoms of hypocalcemia, whether or not Rocaltrol was required, the number of calcium tablets prescribed upon discharge, whether or not postoperative tetany occurred, and calcium levels 1 month after discharge. Each outcome was analyzed using a logistic regression. Graves' disease patients had a significantly (p-value < 0.001) higher odds of greater number of calcium tablets prescribed upon discharge. Further, 6 of 68 patients with Graves' disease and no patient in the control group were readmitted with tetany (p = 0.033). There was a trend, though not significant, toward patients with Graves' disease having a higher prevalence of hypocalcemia the day after thyroidectomy and 1 month later. Patients with Graves' disease are more likely to require increased dosages of calcium as well as experience tetany postoperatively than patients undergoing total thyroidectomy for other indications. This suggests that patients operated upon for Graves' disease warrant close followup as both inpatients and outpatients for signs and symptoms of hypocalcemia.

Gipoparatireoz i katarakta

The causes and mechanisms of cataract development are not studied well enough up to the present. Hypoparathyroidism is characterized by the decrease of parathyroid glands function and decrease of parathyroid hormone production in the most cases. The main clinical manifestation of hypoparathyroidism is a low serum calcium level. Cataract is one of the most important but not well studied complications of hypoparathyroidism. According to clinical researches the cause of cataract development is post-operative hypoparathyroidism which caused post-operative tetany. There is a latent development of hypoparathyroidism apart from manifestation form with tetany, when the ion pomp lens dysfunction is the basic in pathogenesis of cataract development. Besides, cataract may be caused by long-standing hypocalcaemia associated with hyperphosphathemia, that results to the landing of mineral ion deposits in the lens. Thus, there is progressive cataract with hypocalcaemia, though pathogenesis is not studied in a detailed way at present. Nevertheless, the normal serum calcium level can present cataract development. So, early diagnosis and treatment of hypocalcaemia may be useful in controlling the development of cataract.

Intraoperative parathyroid hormone levels measured by intact and whole parathyroid hormone assays in patients with Graves’ disease

To find out if the whole parathyroid hormone (wPTH) assay has practical advantages over the intact (iPTH) assay in patients with Graves' disease. We measured iPTH and wPTH levels before and after subtotal thyroidectomy in 111 consecutive patients (94 women and 17 men) with Graves' disease. Blood samples for assays were obtained after the induction of anesthesia (basal) and following skin closure (postoperative). There was a significant correlation between wPTH and iPTH in both the basal and postoperative levels. Logistic regression analyses examining the relationship between the reduction in parathyroid hormone (PTH) levels and the incidence of tetany revealed that both the wPTH and iPTH assays were significantly equally predictive of postoperative tetany. We found that both the wPTH and iPTH assays were useful for predicting postoperative tetany in patients with Graves' disease, yielding similar results.

Endoscopic thyroidectomy: Our technique

Minimally invasive surgery is widely employed for the treatment of thyroid diseases. Several minimal access approaches to the thyroid gland have been described. The commonly performed surgeries have been endoscopic lobectomies. We have performed endoscopic total thyroidectomy by the anterior chest wall approach. In this study, we have described our technique and evaluated the feasibility and efficacy of this procedure.Materials and Methods:From June 2005 to August 2006, 15 cases of endoscopic thyroidectomy were done at our institute. Five patients were male and 10 were female. Mean age was 45 years. (Range 23 to 71 years). Four patients had multinodular goiter and underwent near-total thyroidectomy; four patients had follicular adenoma and underwent hemithyroidectomy. Out of the seven patients of papillary carcinoma, four were low-risk and so a hemithyroidectomy was performed while three patients in the high risk group underwent total thyroidectomy. A detailed description of the surgical technique is provided.Results:The mean nodule size was 48 mm (range 20-80 mm) and the mean operating time was 85 min (range 60-120 min). In all cases, the recurrent laryngeal nerve was identified and preserved intact, the superior and inferior parathyroids were also identified in all patients. No patients required conversion to an open cervicotomy. All patients were discharged the day after surgery. All thyroidectomies were completed successfully. No recurrent laryngeal nerve palsies or postoperative tetany occurred. The postoperative course was significantly less painful and all patients were satisfied with the cosmetic results.Conclusions:It is possible to remove large nodules and perform as well as total thyroidectomies using our endoscopic approach. It is a safe and effective technique in the hands of an appropriately trained surgeon. The patients get a cosmetic benefit without any morbidity.

Intraoperative Parathyroid Hormone Assay in Patients with Graves’ Disease for Prediction of Postoperative Tetany

We measured intraoperative parathyroid hormone (IOPTH) levels before and after thyroidectomy in a large group of patients to test whether changes in IOPTH can predict postoperative tetany. Subjects were 111 consecutive patients (94 females and 17 males) with Graves' disease undergoing subtotal thyroidectomy. Blood samples for IOPTH assay were obtained after anesthesia (basal) and following skin closure (postoperative). Data were compared between patients who developed tetany (n = 9) and those who did not (n = 102). There was no significant difference in sex, age, period of antithyroid drug administration, or the weight of the thyroid between the two groups. The preoperative serum calcium level was significantly lower (p < 0.05) and the basal IOPTH significantly higher (p < 0.05) in the tetany group than in the non-tetany group. The IOPTH level was significantly lower (p < 0.005) and the average percent decrease in IOPTH levels was higher (p < 0.001) in the tetany group than in the non-tetany group. A decrease in IOPTH of more than 70% was shown to be 78% sensitive, 94% specific, and 93% accurate, and it has 78% positive predictive value and 94% negative predictive value for the development of tetany. Our study shows that a postoperative decrease of IOPTH level is the most predictive of postoperative tetany of the clinical risk factors investigated. We recommend IOPTH measurement as an adjunct to postoperative management of patients with Graves' disease to assist in preventing hypocalcemia and determining the earliest time for safe discharge.

Randomized study on oral administration of calcitriol to prevent symptomatic hypocalcemia after total thyroidectomy

Background Symptomatic hypocalcemia remains the main postoperative complication after total thyroidectomy. The aim of the present study was to evaluate the role of oral supplementation of calcitriol and calcium salts in preventing severe postoperative hypocalcemia after total thyroidectomy. Methods A consecutive series of patients undergoing total thyroidectomy followed by administration of 500 mg of calcium salts 3 times per day were randomized to 3 different postoperative medical treatments: in group A, .5 μg of calcitriol twice per day was administered to 104 patients; in group B, 1 μg of calcitriol twice per day was administered to 111 patients; and in group C, 202 patients did not receive calcitriol. Results The rate of postoperative tetany in group A was 2.9%, in group B was 0%, and in group C was 7.4% ( P = .03) and the rate of paresthesias was 28.8%, 17.1%, and 22.3%, respectively ( P = .19). At discontinuation of calcitriol/calcium salts treatment, intact parathyroid hormone levels did not significantly differ from the preoperative levels. Receiver operating characteristic (ROC) curve analysis showed that the area under the curve for serum concentration of calcium in predicting postoperative tetany was .749, .858 and .862 on the first, second, and third postoperative day, respectively. The best cut-off value of calcemia for prediction tetany was 7.5 mg/dL, and the rate of severe hypocalcemia on the third postoperative day was 23.1% in group A, 9.9% in group B, and 27.2% in group C ( P = .001). Conclusions Oral administration of 1 μg of calcitriol twice per day and 500 mg of calcium salts 3 times per day after total thyroidectomy significantly decreases the risk of severe postoperative hypocalcemia.

Predictive risk factors for postoperative tetany in female patients with Graves’ disease

BACKGROUND: Postoperative tetany occurs in patients with secondary hyperparathyroidism caused by a deficiency in calcium and vitamin D concomitant with transient hypoparathyroidism induced by surgery. In the present study, we further clarified the risk factors by referring to serum 25-hydroxyvitamin D [25(OH)D] and alkaline phosphatase. STUDY DESIGN: The serum levels of intact parathyroid hormone, calcium and other electrolytes, and 25-hydroxyvitamin D [25(OH)D] were measured preoperatively in 178 female patients with Graves’ disease who underwent subtotal thyroidectomy. RESULTS: Of the 178 female patients, 15 (8.4%) developed tetany. Univariate analysis of 16 possible risk factors showed that 2 were statistically significant: serum 25(OH)D and alkaline phosphatase levels. The incidence of tetany according to the serum levels of 25(OH)D and alkaline phosphatase was 19.1% (9/47) in patients with 25(OH)D ≦ 25 nmol/L and alkaline phosphatase > 155, 11.8% (4/34) in those with 25(OH)D ≦ 25 nmol/L and alkaline phosphatase ≦ 155, 6.7% (2/30) in those with 25(OH)D > 25 nmol/L and alkaline phosphatase > 155, and 0% (0/50) in those with 25(OH)D > 25 nmol/L and alkaline phosphatase ≦ 155. CONCLUSIONS: Patients with Graves’ disease who have vitamin D deficiency with high serum alkaline phosphatase levels are the highest-risk group for postoperative tetany. Serum 25(OH)D and alkaline phosphatase should be monitored in patients with Graves’ disease.

High Prevalence of Vitamin D Deficiency in Japanese Female Patients with Graves' Disease.

We reported previously that vitamin D deficiency is a causal mechanism of postoperative tetany in patients with Graves' disease. The aim of the present study was to determine the prevalence of vitamin D deficiency by reviewing serum 25(OH)D levels in 208 patients with Graves' disease (146 women, 62 men) during a 1 year period. Serum 25(OH)D levels were significantly lower (p < 0.001) in female Graves' patients (31.8 +/- 13.3 nmol/l) than in male patients (41.3 +/- 15.0 nmol/l). Vitamin D deficiency (defined as a serum 25(OH)D value below 25 nmol/l) was found in 40% of female patients and in 18% of male patients (p < 0.005). There was a significant seasonal variation in the 25(OH)D concentrations in female patients [amplitude 6.38 (95% CI, 5.42-7.56)], with values below 25 nmol/l found in 58% of female patients during the winter months. There were significant (p < 0.001) differences in serum 25(OH)D levels between age groups in the female patients. The concentrations were lowest in patients in their twenties (25.1 +/- 8.2 nmol/l) and highest in patients in their fifties and sixties (43.2 +/- 13.7 nmol/l). Serum 25(OH)D concentrations might be monitored in patients with Graves' disease during antithyroid drug therapy, and vitamin D and/or calcium supplements are recommended for patients with vitamin D deficiency.

Calcium and its regulating hormones in patients with graves disease: sex differences and relation to postoperative tetany.

To find out why female sex is the most important risk factor for tetany, as calcium and bone metabolism may differ between the sexes. Prospective study. Thyroid centre, Japan. 45 men (mean age 35 years, SD 13) and 178 women (mean age 33 years, SD 12) with Graves disease treated by subtotal thyroidectomy. Measurement of serum concentrations of intact parathyroid hormone (iPTH), calcium, electrolytes, 25-hydroxyvitamin D (25 (OH) D), and 1,25-dihydroxyvitamin D (1,25 (OH) 2D). Mean values of these substances, together with reductions in serum calcium concentration, relative youth, increased alkaline phosphatase activity, large goitre, and increased serum TSH binding inhibitory globulin concentration. Women had significantly lower calcium concentrations than men (mean (SD) 2.37 (0.13) compared with 2.43 (0.07), p = 0.003). Serum calcium concentrations correlated significantly with concentrations of 25 (OH) D (p < 0.001). 121 of the women (68%) compared with 13 (29%) of men had vitamin D deficiency as defined as 25 (OH) D < 25 nmol/l (p < 0.05). 15 patients (8%) developed tetany postoperatively compared with I man (2%, p = 0.2). Women with Graves disease are more susceptible to calcium and vitamin D deficiency than men, which may account for the higher incidence of postoperative tetany among women with the disease.

Seasonal changes in calcium homeostasis affect the incidence of postoperative tetany in patients with Graves' disease

Background: We have found that postoperative tetany occurs in patients with Graves' disease who have secondary hyperparathyroidism caused by a deficiency in calcium and vitamin D concomitant with transient hypoparathyroidism after surgery. There are seasonal variations in serum 25-hydroxyvitamin D (25[OH]D) concentrations. The purpose of this study was to investigate the effects of seasonal changes in calcium homeostasis on the incidence of postoperative tetany in patients with Graves' disease who undergo subtotal thyroidectomy. Patients and Methods: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25(OH)D, and 1,25-dihydroxyvitamin D (1,25[OH] 2D) in female patients with Graves' disease who underwent subtotal thyroidectomy during the summer (n = 89) and during the winter (n = 89). Results: The serum levels of calcium, magnesium, and 25(OH)D were significantly higher, but iPTH levels and 1,25(OH) 2D levels were lower in summer than in winter. The percentage of vitamin D deficiency (25(OH)D < 25nmol/L) was 23% in summer and 62% in winter (P < .001). iPTH was below the detection limit on the first postoperative day in 15 patients (13.8%) in summer and in 13 patients (11.4%) in winter. In summer, tetany developed in only 4 of 15 patients and in one patient whose iPTH level was below normal (incidence of tetany, 5.6%). In winter, however, tetany developed in 6 of 13 patients and in 4 patients whose iPTH level was below normal (incidence of tetany, 11.2%). Conclusions: Patients with Graves' disease are more susceptible to calcium and vitamin D deficiency during the winter than during the summer, resulting in the tendency toward a higher incidence of postoperative tetany in winter. (Surgery 2000;127:377-82.)

Postoperative tetany in patients with Graves' disease: a risk factor analysis.

There is little information regarding the clinical risk factors for postoperative tetany in patients with Graves' disease. We analysed the risk factors responsible for postoperative tetany by univariate and multivariate analysis in thyroidectomized patients with Graves' disease, and we discuss the mechanisms of hypocalcaemia and tetany after surgery. The subjects were 1742 consecutive patients with Graves' disease who underwent subtotal thyroidectomy between 1992 and 1994. Univariate analysis of 15 possible risk factors demonstrated that 10 were significant: sex, required operation time, blood loss, preoperative serum calcium level, estimated weight of thyroid remnant, size of goitre, amount of excised thyroid tissue, serum alkaline phosphatase concentration, age at operation and TSH-binding inhibitory immunoglobin (TBII). In multivariate analysis in female patients, the risk factors were: preoperative lower serum calcium level, younger age, higher serum alkaline phosphatase concentration, larger size of goitre and higher value of TBII, in order of decreasing probability of significance. These results, combined with previous observations in which a significant decline in serum parathyroid hormone level was found in patients with Graves' disease who suffered postoperative tetany, suggests that postoperative tetany may occur during the period of bone restoration due to antithyroid drug therapy and be due to continuation of a calcium flux bone concomitant with transient hypoparathyroidism induced by surgery. Calcium supplements during preoperative period and/or after surgery may be appropriate for patients who are anticipated to develop postoperative tetany based on these risk factors.

The Mechanism of Postoperative Tetany in Graves' Disease

The levels of serum calcium (Ca), inorganic phosphate (P) and mid-molecular parathyroid hormone (PTH) were measured in 37 patients with Graves' disease (12 in hyperthyroid state, 25 in euthyroid state followed by subtotal thyroidectomy), 6 with papillary carcinoma of the thyroid, 8 with benign nodular goiter and 19 healthy control subjects in order to investigate the change in these levels before and after thyroidectomy. The levels of serum Ca and P of the hyperthyroid patients with Graves' disease were 9.73 +/- 0.30 mg/dl and 4.47 +/- 0.44 mg/dl, respectively, which were significantly higher than those of healthy control subjects. No significant difference in the levels of serum PTH was observed between hyperthyroid patients with Graves' disease and healthy control subjects. The levels of serum Ca, P and PTH of euthyroid patients with Graves' disease were not significantly different from those of healthy control subjects. In the patients with Graves' disease who had undergone subtotal thyroidectomy followed by postoperative tetany, serum Ca and serum PTH decreased significantly from 9.39 +/- 0.45 mg/dl to 7.90 +/- 0.33 mg/dl and from 406.6 +/- 164.4 pg/ml to 229.9 +/- 136.0 pg/ml, respectively, after surgery, but there was no change in serum P. In the patients without postoperative tetany, serum Ca and serum P decreased significantly after surgery from 9.65 +/- 0.36 mg/dl to 9.15 +/- 0.33 mg/dl and from 4.03 +/- 0.46 mg/dl to 3.47 +/- 0.54 mg/dl, respectively, without any change in the levels of serum PTH. In the patients with papillary carcinoma or benign nodular goiter without postoperative tetany, the levels of serum Ca, P and PTH did not change after surgery. In the patients with papillary carcinoma followed by postoperative tetany, serum Ca decreased significantly after surgery with concomitant decrease of serum PTH. It was concluded that excessive thyroid hormones influenced Ca metabolism, and the transient tetany following subtotal thyroidectomy for Graves' disease seemed to be due to both the absorption of Ca by hungry bone and parathyroid hypofunction.

Surgical management of renal hyperparathyroidism in the dialysis patient

Over 12 years, 49 patients with hyperparathyroidism secondary to chronic renal failure under treatment with hemodialysis were treated with total parathyroidectomy. A portion of one gland was implanted in the sternocleidomastoid muscle. The operative indications were elevation of parathormone, serum calcium, and phosphorus levels, pruritis, bone pain, pathologic fractures, and myalgia. Special postoperative complications discussed are hyperkalemia, hemorrhage, and respiratory obstruction. There were no operative deaths. No postoperative tetany was seen. Total parathyroidectomy should be performed in chronic renal failure patients with persistent elevation of serum calcium and parathormone levels, and who have pain, fractures, or soft tissue calcification. All postoperative parathyroidectomy patients should be observed for possible hyperkalemia.

Parathyroid microautotransplantation and the viscerovertebral angle.

Conservation of physiologic values of circulating parathormone is a surgical objective in those instances in which a hyperfunctional parathyroid state exists as well as in those instances in which cervical evisceration employed as an ablative measure for the management of neoplastic disease threatens to impose postoperative tetany. Because the parathyroid glands may vary in number and in anatomic sites, a predictable and reproducible surgical approach that permits the operator an avenue of access to these structures is used. The viscerovertebral angle provides a surgical modality which facilitates the operative effort. The method has been applied in more than 70 patients.

The “parathyroid blush” in the identification of parathyroid glands

When part of a parathyroid gland is excised for biopsy, the cut surface remaining becomes diffusely red from microscopic bleeding in one to three seconds, the “parathyroid blush.” By this simple observation the surgeon can distinguish grossly similar structures such as lobular fat from parathyroid tissue. Advantages include consistency, shortened operating time, fewer frozen section confirmations needed, reliability as a teaching aid, and safety, especially in avoiding postoperative tetany.

THE INCIDENCE OF HYPOPARATHYROID TETANY AFTER THYROID OPERATIONS: RELATIONSHIP TO AGE, EXTENT OF RESECTION AND SURGICAL EXPERIENCE

In a series of 2,513 thyroid operations performed at the Royal Brisbane Hospital between July 1, 1944, and June 30, 1964, postoperative tetany occurred in 19 cases (0·76%). The incidence was significantly higher in younger patients, after more extensive resections and with less experienced surgeons. One or more of these adverse factors was present in every case, the last being most common. The data were insufficient to confirm or exclude a relationship to the sex of the patient, the type of thyroid disease, or the type of preoperative medical treatment. During the period reviewed, the average number of operations per year fell from 161 to 63, the average number of operations per surgeon per year fell from 18 to five, and the expected percentage of patients operated on by adequately experienced surgeons fell from 80 to 30. In the five years ending June 30, 1969, the incidence of postoperative tetany was 3·8%, a fivefold increase compared with the preceding 20 years, and it is suggested that this reflected the lesser experience of thyroid surgery of present-day surgeons compared with those of 20 years ago. The only satisfactory way of reversing this trend would be by an agreement amongst surgeons to reduce the number who regularly undertake thyroid surgery in proportion to the reduced number of operations needed. The incidence of postoperative tetany would also be reduced if radical resection for hyperthyroidism was discontinued, and If surgery was avoided in patients aged under 30 years except after failure of medical treatment.

Crystals in the lens.

Crystal formation in the lens in both the young and the aged has been reported by various observers from time to time. The morphology and the chemical nature of the crystals are also of varied nature; for example, Goulden12and other observers have described crystalline opacities in the lens showing green and blue iridescence in morbid conditions such as thyroid dysfunction, postoperative tetany, mongolian idiocy, and myotonia atrophica. Vogt26as mentioned by Parker22has described a spear cataract consisting of shiny crystalline needles. Riad24has reported a pedigree with lens crystals which looked like tiny broken glass fragments, rectangular in shape, with a notch at one corner. Verhoeff reported a case in which protein crystals produced the picture of coralliform cataract.30Among the varied chemical constituents of the crystals, cholesterol is frequently found in different types of senile, traumatic, and complicated cataracts. The spear cataract

Insensitivity to Vitamin D

The authors observed that some patients being treated for postoperative tetany became insensitive to doses of vitamin D which had been adequate to maintain the plasma calcium levels and normal levels could no longer be maintained even with large doses of vitamin D. When a change was made from large doses of vitamin D to normal doses of A. T. 10 (dihydrotachysterol) or vitamin D3 the levels of calcium in the plasma could again be restored to normal. Thus there appeared to have developed an insensitvity to one form of vitamin D but not to closely related substances. This finding may have far-reaching implications in understanding other disorders such as vitamin D resistent rickets. The phenomenon appears to be unique as regards the action of vitamins.