PHOSPHATE EXCRETION AND PARATHYROID FUNCTION AFTER RADIOIODINE THERAPY AND THYROIDECTOMY

Journal Article · Thu Aug 01 04:00:00 EDT 1963 · Clinical Science (England) Changed to Clin. Sci. Mol. Med.

OSTI ID:4069144

Harden, R M; Harrison, M T; Alexander, W D

It has been previously suggested that therapeutic doses of radioiodine may damage the parathyroid glands, but the association of hypoparathyroidism with radioiodine therapy in man has only rarely been reported. Moreover, in these patients it was not clear whether radioiodine was responsible for the hypoparathyroidism, and animal experiments have yielded conflicting results. In attempts to resolve this problem, measurements were made of the response of the parathyroid glands to a high-phosphate diet in four groups of patients: a control group without evidence of parathyroid or thyroid disease; patients with clinical features of hypoparathyroidism; a group after surgical thyroidectomy; and a group treated with radioiodine (6 to 300 mC I/sup 131/). In the second group no response by the parathyroids to a phosphate load was found and in the third and fourth groups a subnormal response was noted. As a measure of the response of the parathyroid glands to high-phosphate feeding, the phosphate excretion index (PEI) was used. The serum Ca level was significantly lower in the post- thyroidectomy group when compared with the control group, but in the group treated with I/sup 131/, it was not significantly different from the control group. A review of reports of earlier cases shows that although hypoparathyroidism following thyroidectomy is well recognized it has rarely been described following therapy' with radioiodine. In man, the parathyroid glands are generally situated on the surface of the thyroid, sometimes lying within its capsule. On occasion, they may lie partially within the thyroid gland, and, rarely, may be completely- surrounded by it. In the latter circumstance a parathyroid gland would receive a greater radiation dose than parathyroids in the more usual sites. It is calculated that a completely embedded parathyroid gland receives about twice as much radiation as one situated on the surface of the thyroid. Other factors may be the size and the radioiodine uptake of the thyroid gland and variations in radiosensitivity of the parathyroid glands. In the present group of I/sup 131/ -treated patients the response of the parathyroids to phosphate feeding was subnormal, although the serum Ca and control PEI did not differ significantly from those of the control group. It is concluded that diminished parathyroid reserve may result from radioiodine therapy and thyroidectomy. The possibility that damage to one parathyroid gland by radiation, by trauma during surgery, or by pressure from a large goiter, may result in the formation of antibodies which lead to the destruction of the remaining parathyroid glands is discussed. (BBB)

• Research Organization: Western Infirmary, Glasgow
• NSA Number: NSA-18-015926
• OSTI ID: 4069144
• Journal Information: Clinical Science (England) Changed to Clin. Sci. Mol. Med., Journal Name: Clinical Science (England) Changed to Clin. Sci. Mol. Med. Vol. Vol: 25; ISSN CSCIA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANIMALS
ANTIBODIES
BIOLOGY AND MEDICINE
BLOOD SERUM
CALCIUM
DIET
DISEASES
GLANDS
IMMUNITY
IODINE 131
MAN
METABOLISM
PARATHYROIDS
PHOSPHATES
QUANTITY RATIO
RADIATION INJURIES
RADIOSENSITIVITY
RADIOTHERAPY
SURGERY
THYROID