Radionuclides and therapy of thyroid cancer.

The majority of thyroid carcinomas are removed surgically. The appropriate surgical technique is still debated. After surgery the amount of residual thyroid or tumour and the presence of local or distant metastases is often in doubt, particularly if it is not detectable clinically. Therefore, methods for determining the presence of disease or the later recurrence of disease are needed. They commonly include serum thyroglobulin and imaging after diagnostic or therapeutic doses of 131I. Other techniques are used such as 131I whole body retention (using a whole body counter), 201Tl and 99Tcm-sestamibi imaging. The place of these diagnostic methods in the management of thyroid cancer is reviewed in this article. Radioiodine would seem an ideal treatment for recurrence of functioning thyroid carcinoma as 131I targets the lesion and has minimal side effects. However, the indolent nature of well-differentiated thyroid carcinomas makes it difficult to assess the benefits of radioiodine therapy both in its ability to ablate the normal thyroid and to treat recurrent and metastatic disease. However, the addition of radioiodine therapy to local surgical removal reduces both the occurrence of metastases and the morbidity with prolonged follow-up. Unresolved issues that remain concern the activities of radioiodine needed to achieve adequate ablation of residual thyroid tissue and to treat residual and recurrent cancer. There is also debate as to exactly which patients require radioiodine therapy. This review also considers radiation protection and the side effects of 131I therapy.

Clinical versus biochemical assessment in thyroxine replacement therapy: a retrospective study.

A retrospective audit of a thyroid clinic revealed that only 67% of clinical assessments of thyroid status in patients receiving thyroxine replacement therapy were correct. The identification of patients on excessive doses of thyroxine appears to be the most difficult by clinical assessment alone, only 10% of those patients with a suppressed TSH level being identified. This study emphasises the importance of thyroid function tests in the assessment of patients on thyroxine replacement.

Diurnal variation in TSH and free thyroid hormones in patients on thyroxine replacement.

Eleven patients with treated hypothyroidism were investigated to examine the effects of time on their thyroid function tests. Each patient was clinically and biochemically euthyroid on once daily thyroxine replacement therapy, taken in the morning. TSH followed a diurnal rhythm with a peak level at 23.30 h and a trough level at 14.30 h. Four subjects had TSH trough levels within the normal range, but with peak levels outside this range. FT4 and FT3 levels fell from their highest levels some three hours after ingestion to the lowest levels just prior to the next dose. This study shows that there are significant time-related variabilities in TSH and thyroid hormone levels in treated hypothyroid patients. This should be taken into account when interpreting results of their thyroid function tests.

Nephrotic syndrome and hepatitis in early syphilis.

A 54 year old man presented with features of acute hepatitis and the nephrotic syndrome. A diagnosis of active syphilis was only made by chance after extensive investigation. Syphilis should be considered in the differential diagnosis of both acute hepatitis and the nephrotic syndrome occurring separately as well as together.

Gastric mucosal cell loss caused by aspirin and alcohol.

Gastric epithelial cell loss was studied in healthy volunteers before and after intragastric instillation of four aspirin (ASA) formulations and three strengths of alcohol. Each test solution was administered three times over a period of three hours during one of the experiments. Three of the four aspirin formulations significantly increased gastric epithelial cell loss. Microencapsulated aspirin increased gastric epithelial cell loss significantly, but only after the third dose. Alcohol, 10% (wine), increased cell loss to a similar extent as did microencapsulated aspirin. Alcohol, 20% (campari), and 40% (whisky), significantly enhanced cell loss to such a degree as was elicited by the two strengths of soluble aspirin. Thus, gastric cell loss increased dose-dependently after both aspirin and alcohol. The data suggest that, in man, gastric epithelial cell damage caused by different aspirin formulations and alcohol concentrations is reproducible and dose-dependent.

Alveolar permeability in HIV antibody positive patients with Pneumocystis carinii pneumonia.

Pulmonary permeability was assessed using the technique of 99mTc (technetium-99m) diethylene triamene pentacetic acid (DTPA) aerosol transfer in 10 patients who had antibodies to human immunodeficiency virus (HIV) and were non-smokers and in 20 HIV antibody positive smokers. Five patients had Pneumocystis carinii pneumonia (PCP) proved by transbronchial lung biopsy; four were non-smokers and one a smoker. Two findings emerged: patients with PCP had greater epithelial permeability than non-smokers and smokers; and the permeability curves were monophasic in smokers and non-smokers, but biphasic in patients with PCP. The biphasic curve observed is indicative of diffuse alveolar damage and might be useful to predict PCP in patients with antibodies to HIV who have normal chest radiographs. As the study was of only five patients with PCP, however, further studies are necessary to confirm this observation.

Pulmonary permeability in hematologic malignancies. Effects of the disease and cytotoxic agents.

Pulmonary permeability was assessed using the technique of DTPA aerosol transfer in untreated patients with chronic lymphocytic leukemia (CLL) and in patients with a variety of hematologic malignancies that had all been treated with alkylating agents. Two findings emerged: In the untreated CLL patients, the permeability of the upper and middle lung regions was reduced. This may be due to diffuse infiltration by the CLL; and Treatment with cytotoxic agents increased epithelial permeability in both middle and lower lung regions. Further prospective studies are required to determine the cause of the long T50 values in untreated CLL and to confirm that the DTPA transfer test is a sensitive indicator of the damage which eventually leads to pulmonary fibrosis.

Functional images of lung 99Tcm-DTPA aerosol transfer in smokers and nonsmokers.

The large amount of information from dynamic 99Tcm-DTPA lung can be simplified and rendered easily interpretable by the use of functional images. Eight such images have been devised: a maximum count image, a minimum count image, a time of maximum count image, a time of minimum count image, percentage maximum change image, a T50 image, a standard error image and a correlation coefficient image. These images enable the distribution of aerosol after inhalation, the reliability of the calculated T50 value and movement artefacts to be easily identified. They also allow rapid assessment of the distribution of T50 values in the lungs which may be particularly useful in segmental lung disease.

Isotope lymphography: a new method of investigating the role of the lymphatics in chronic limb oedema.

A method of investigating the lymphatic system by radionuclide imaging in patients with chronic lower limb oedema is described. The clearance of 99mTc rhenium sulphur colloid from the interdigital space of 55 limbs and its appearance in the ilio-inguinal lymph nodes 30 min, 1, 2 and 3 h later has been measured using a gamma camera in 34 limbs (26 patients) with the clinical and radiological features of primary lymphoedema, 10 limbs (8 patients) with venous oedema and 12 control limbs (6 volunteers). On visual interpretation the sensitivity of this technique in diagnosing lymphoedema was 97 per cent and its specificity 100 per cent, while it clearly differentiated between lymphoedema and venous oedema. Estimation of the percentage uptake of the colloid in the ilio-inguinal lymph nodes at 1/2, 1, 2 and 3 h showed a markedly decreased lymph flow in the 34 lymphoedematous limbs and an increased flow in the 10 limbs with venous oedema. The results suggest that this technique can be used as a simple diagnostic outpatient technique in the investigation of chronic limb oedema.

Regional lung epithelial leakiness in smokers and nonsmokers.

In order to measure regional lung 'leakiness' we have adapted a method developed by Jones et al., to correct for background in the estimation of regional lung transfer of DTPA. It is clear from our study that the half time transfer values (T50) alter from the apex to the base of the lungs in both smokers and nonsmokers. The mean apical T50 values are 56.0 and 56.7 min for the right and left lung respectively in nonsmokers and 12.5 and 12.6 min in smokers. The basal T50 values are 77.5 and 76.9 min for the right and left lung respectively in nonsmokers and 24 and 24.2 min in smokers. These figures suggest that cigarette smoke affects all lung regions and that the transfer values in the apices are more rapid than in the bases in both smokers and nonsmokers.

Lung 99Tcm-DTPA transfer: a method for background correction.

A method to correct for background in lung DTPA transfer has been developed for use with a large field of view gamma camera. The method gives comparable values of T50 to those obtained by Jones et al. The correction factors vary from apex to base; therefore to allow intersegmental T50 comparisons each segment should be corrected for background using its own correction factor.

Familial abnormalities of thyroxine binding proteins: some problems of recognition and interpretation.

A three generation family study was carried out after inappropriate treatment with radioactive iodine of a 50 year old woman with a raised serum total thyroxine concentration and free thyroxine index. Subsequent investigations showed that she and five members of her family had raised thyroxine binding globulin concentrations. Free thyroxine and free triiodothyronine concentrations were normal. Problems encountered in the recognition of this thyroxine binding protein disorder are discussed. Clinicians and clinical biochemists should be aware of these pitfalls and thus avoid further incorrect treatment on the basis of biochemical findings, even though free hormone estimations are now becoming readily available.

Lugol's iodine: its effect on thyroid blood flow in patients with thyrotoxicosis.

It has been established practice for 60 years to prepare thyrotoxic patients undergoing thyroidectomy with Lugol's iodine. However, evidence in support of its claimed benefits, namely a reduction in the vascularity and friability of the toxic thyroid gland, is scanty. We have therefore determined the effect of Lugol's iodine on thyroid blood flow, as measured by thyroid uptake of thallium-201, in nine patients with Graves' disease and one euthyroid patient. Thallium-201 uptake, as well as serum thyroxine and triiodothyronine, fell significantly after treatment with iodine. Although not correlated with thyroid function tests, thallium-201 uptake was significantly correlated with thyroid weight. These results support the contention that thyroid blood flow is reduced in thyrotoxic patients treated with Lugol's iodine.