Unusual presentations of acanthosis nigricans and insulin resistance in a brother and sister.
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Biomedical subjects
Publications and source records attributed to A B Atkinson.
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Amiodarone is a widely used antiarrhythmic drug, which contains 75 mg of iodide per 200 mg of active substance. Eight of our patients receiving long-term amiodarone therapy became hypothyroid. Seven of these patients had no previous history of thyroid dysfunction or goiter. Antithyroid antibodies were absent, and standard perchlorate discharge tests were positive in seven patients when hypothyroidism was diagnosed. In one patient, amiodarone therapy was withdrawn; over the next nine months, the hypothyroidism resolved, and results of the perchlorate discharge test reverted to normal. We conclude that amiodarone-induced hypothyroidism is similar to previously described iodide-induced hypothyroidism. It may develop in the absence of a previous history of thyroid disease, and all patients receiving long-term amiodarone therapy should therefore be regularly monitored for hypothyroidism.
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Prolactin secretion in response to TRH has been assessed in six patients with isolated gonadotrophin deficiency (IGD) and in eight normal controls. In all six subjects with IGD, serum oestradiol was below the detection limit of the method. There was no statistical difference between either the basal or maximum increment of serum prolactin between the two groups. Recent claims that prolactin responses to TRH distinguish constitutional delay of puberty from IGD have therefore not been supported.
A patient with ACTH-dependent Cushing's syndrome remained in clinical and biochemical remission six years after pituitary irradiation and while on bromocriptine therapy. When bromocriptine was discontinued urinary free cortisol values became elevated, and were not suppressed by dexamethasone. After reintroduction of the drug, remission was again obtained. It is concluded that bromocriptine is responsible for continuing longterm remission in this case. The possible use of bromocriptine as an adjunctive therapy in ACTH-dependent Cushing's syndrome is discussed.
A 71-yr-old woman with clinical signs of Cushing's syndrome was studied continuously for an extended period after demonstration of a paradoxical response to dexamethasone. She proved to have a corticotroph cell adenoma of the pituitary which caused secretion of ACTH and cortisol in two distinct rhythms. One rhythm consisted of a period of 40 days of excess cortisol production, followed by a period of 60-70 days of normal production. During the period of excess cortisol production there was a second rhythm, consisting of peaks of cortisol production every 3-6 days with intervening troughs of normal cortisol production. Prolonged clinical remission followed transphenoidal surgery, but the pituitary still has the ability to provoke abnormal amounts of cortisol secretion, as occurred during a postoperative dexamethasone suppression test. The long duration of normal cortisol production phases in this patient demonstrates the difficulty in excluding Cushing's syndrome in patients with suggestive clinical symptoms but normal serum and urinary cortisol levels if these tests are measured for a single short phase of several days.
A 37 year old male with a strong family history of autoimmune disease presented with typical symptoms of hyperthyroidism. He had exophthalmos but no goitre. Hyperthyroidism was confirmed by failure of 131I neck uptake to suppress after 7 days treatment with triiodothyronine. Six years previously a diagnosis of primary hypothyroidism has been made. At diagnosis of hyperthyroidism, thyroglobulin antibodies, thyroidal microsomal antibodies and thyroid stimulating immunoglobulins were detected. The absence of thyroid growth stimulating immunoglobulins and presence of immunoglobulins blocking TSH-induced growth may account for the absence of goitre throughout. HLA -B8, -B, -DR3 and -DR4 genotypes, low C4 complement concentrations and islet cell autoantibodies were detected at the time of diagnosis and 1 year later diabetes mellitus developed.
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Forty four subjects (23 obese controls, 11 patients with possible Cushing's syndrome, and 10 patients with definite Cushing's syndrome) underwent low dose (0 X 5 mg every six hours for two days) dexamethasone suppression tests during which serum cortisol concentration at 0800 and excretion of urinary free cortisol over 24 hours were measured. Serum cortisol concentration fell to below 60 nmol/1 (2 X 2 micrograms/100 ml) in 31 subjects and remained above 250 nmol/1 (9 X 1 micrograms/100 ml) in the 13 others. Excretion of urinary free cortisol showed a similar response, falling to below 110 nmol (40 micrograms)/24 h in 31 and remaining above 180 nmol (65 micrograms)/24 h in the 13 others. There was complete concordance between the two variables in terms of the pattern of response. Serum cortisol concentration fell to below 60 nmol/1 (2 X 2 micrograms/100 ml) in at least 97% (31 of a possible 32) of subjects without Cushing's syndrome. On the other hand, a serum cortisol concentration of above 250 nmol/1 (9 X 1 micrograms/100 ml) after low dose dexamethasone gave a false positive diagnosis of Cushing's syndrome in at most only one of 13 patients (7 X 7%). Measurement of serum cortisol concentration during the low dose dexamethasone test is simpler than, and as accurate and reliable as, measurements of urinary steroids.
A case of metastatic phaeochromocytoma is presented. Meta-iodobenzylguanidine was used to locate the tumour but failed to show two functioning abdominal metastatic deposits. Although meta-iodobenzylguanidine appears to be highly specific for phaeochromocytoma, a negative scan does not exclude a functioning tumour with confidence.
A six-year prospective study of 144 newly diagnosed, symptomatic diabetic patients aged 40-69 years showed that 21 (15%) required insulin therapy, commencing 1-61 months after diagnosis. The plasma insulin response to oral glucose was assessed at the time of diagnosis. All 12 patients with very low peak insulin response (less than or equal to 6 mU/l) required insulin therapy. Thirty-six patients had an intermediate insulin response (greater than 6 less than or equal to 18 mU/l); of these, 7 with a mean weight 88% (range 73-96%) of average body weight required insulin, while 29 with a mean weight 117% (range 98-158%) of average body weight, did not. Ninety-six patients had a peak insulin response (greater than 18 mU/l); 2 patients whose weights were 96% and 100% of average body weight, required insulin, while the remainder did not. Consideration of initial body weight and peak insulin response provides a useful prediction of the eventual need for insulin.
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Fifteen patients with hypertension and unilateral renal artery disease were treated with captopril alone; 10 came to operation and were later assessed postoperatively with no drug treatment. Captopril caused both immediate and sustained decreases in plasma angiotensin II and aldosterone, with increases in plasma active renin and blood angiotensin I concentrations. Decrements in systolic and diastolic pressure 2 hours after the first dose of captopril were closely correlated with the initial decreases in plasma angiotensin II. Blood pressure was decreased by long-term captopril therapy irrespective of whether plasma angiotensin II was abnormally high before treatment. The long-term response of both systolic and diastolic pressure correlated well with the response to surgery. By contrast, the blood pressure decrease 2 hours after the initial dose of captopril variously underestimated and overestimated the decrease during prolonged use of the drug and did not relate to surgical outcome. In patients who, before treatment, had secondary aldosteronism, hyponatremia, hypokalemia and sodium and potassium deficiency, captopril corrected these abnormalities. In the remaining patients, long-term captopril therapy did not alter exchangeable sodium, plasma sodium or total body potassium, although plasma potassium levels increased.
The angiotensin converting-enzyme inhibitor captopril was used as long-term preoperative treatment in a series of hypertensive patients with unilateral renal arterial disease. There were immediate and sustained falls in plasma angiotensin II and aldosterone concentrations, with converse increases in circulating renin and angiotensin I. In patients with sodium and potassium deficiency and secondary aldosterone excess before treatment captopril corrected the sodium and potassium deficits; in these cases the initial hypotensive response was profound but the later effect was less pronounced. When sodium and potassium state was initially normal it remained unchanged during captopril treatment, while the full hypotensive effect took up to three weeks to be attained. The immediate, but not long-term, falls in arterial pressure with captopril were proportional to the immediate decrements of plasma angiotensin II. Nevertheless, while the immediate blood-pressure reduction with captopril variously overestimated and underestimated the eventual surgical response, the absolute blood-pressure values during long-term captopril related well with those after operation. Pretreatment plasma renin and angiotensin II concentrations, while closely predicting the immediate captopril response, are fallible guides to surgical prognosis. In contrast, long-term treatment with converting-enzyme inhibitors may provide an accurate indication of surgical outcome.
1 The ability of captopril, 150 mg three times daily by mouth, to effect sustained reduction in plasma angiotensin II, with converse increases in circulating angiotensin I, and in active, inactive and total renin concentrations, has been assessed. 2 During prolonged treatment with captopril alone, and 12 h after the last dose of the drug, plasma angiotensin II remained approximately one-sixth of basal concentrations, while angiotensin I and renin concentrations were proportionately increased. However, further increases in angiotensin I, and in active, inactive and total renin concentrations, were seen 2 and 6 h after the morning dose of 150 mg captopril. 3 Inter-dose variations in plasma aldosterone and blood pressure were not closely related to concurrent variations in the renin-angiotensin system. 4 Arguments are presented for relying on measurements of plasma renin and angiotensin concentrations rather than of renin activity or aldosterone in assessing the effectiveness of converting enzyme inhibition.
Intravenous urography is the standard screening test for renovascular hypertension but there is a significant incidence of false negative and false positive results. In an attempt to improve the detection rate, indomethacin was administered orally to nine patients with renal artery stenosis (proven by arteriography and by divided ureteric function studies) before rapid-series intravenous urography. This urogram was compared independently by two observers with prior similar-series urograms. Indomethacin did not alter diagnostic accuracy.
Spironolactone alone in full dosage failed to correct hypertension in a patient with Conn's syndrome and renal impairment, although the previously increased total exchangeable sodium fell to normal and the previously suppressed plasma angiotensin II did not rise above the normal range. Addition of the converting enzyme inhibitor captopril reduced plasma angiotensin II to very low levels, with a slight further fall in exchangeable sodium. Blood pressure was well controlled. Because hypertension in Conn's syndrome resistant to spironolactone usually also responds poorly to removal of the adenoma, and is difficult to treat with conventional hypotensive agents, the combination of a converting enzyme inhibitor with a potassium conserving diuretic is worthy of trial in such cases.