Symptomatic hyponatremia in association with a low-iodine diet and levothyroxine withdrawal prior to I131 in patients with metastatic thyroid carcinoma.

BACKGROUND: Strategies to improve I131 uptake in thyroid carcinoma include levothyroxine (LT4) withdrawal or thyrotropin (TSH) administration along with a low-iodine diet. We report five patients with papillary or follicular thyroid carcinoma who developed symptomatic hyponatremia during LT4 withdrawal and low-iodine diet. RESULTS: Four patients had pulmonary and/or brain metastases. All had restricted iodine intakes during LT4 withdrawal. Presenting complaints included weakness, dizziness, fainting spells, lethargy, and/or nausea. Baseline serum sodium levels while on LT4 suppression were normal. During presentation all were hypothyroid and serum sodium ranged from 110 to 121 mmol/L (normal 135-148). Despite hyponatremia, the plasma renin activity and serum aldosterone levels were suppressed, indicating volume expansion. The hyponatremia responded to fluid restriction and normalized after LT4 replacement. Low sodium intake, inappropriate antidiuretic hormone secretion syndrome (SIADH)-like disorder secondary to hypothyroidism and/or lung or cerebral metastases may have contributed to hyponatremia. CONCLUSIONS: The development of hyponatremia during LT4 withdrawal and low-iodine diet in otherwise healthy patients with thyroid carcinoma is extremely rare. However, elderly patients with metastatic thyroid carcinoma need observation during LT4 withdrawal combined with a low-iodine diet and should receive instruction to take iodine-free sodium chloride. Free water restriction may be necessary in some patients.

Effect of a high saturated fat and no-starch diet on serum lipid subfractions in patients with documented atherosclerotic cardiovascular disease.

OBJECTIVE: To determine whether a diet of high saturated fat and avoidance of starch (HSF-SA) results in weight loss without adverse effects on serum lipids in obese nondiabetic patients. PATIENTS AND METHODS: Twenty-three patients with atherosclerotic cardiovascular disease participated in a prospective 6-week trial at the Christiana Care Medical Center in Newark, Del, between August 2000 and September 2001. All patients were obese (mean +/- SD body mass index [BMI], 39.0+/-7.3 kg/m2) and had been treated with statins before entry in the trial. Fifteen obese patients with polycystic ovary syndrome (BMI, 36.1+/-9.7 kg/m2) and 8 obese patients with reactive hypoglycemia (BMI, 46.8+/-10 kg/m2) were monitored during an HSF-SA diet for 24 and 52 weeks, respectively, between 1997 and 2000. RESULTS: In patients with atherosclerotic cardiovascular disease, mean +/- SD total body weight (TBW) decreased 5.2%+/-2.5% (P<.001) as did body fat percentage (P=.02). Nuclear magnetic resonance spectroscopic analysis of lipids showed decreases in total triglycerides (P<.001), very low-density lipoprotein (VLDL) triglycerides (P<.001), VLDL size (P<.001), large VLDL concentration (P<.001), and medium VLDL concentration (P<.001). High-density lipoprotein (HDL) and LDL concentrations were unchanged, but HDL size (P=.01) and LDL size (P=.02) increased. Patients with polycystic ovary syndrome lost 14.3%+/-20.3% of TBW (P=.008) and patients with reactive hypoglycemia lost 19.9%+/-8.7% of TBW (P<.001) at 24 and 52 weeks, respectively, without adverse effects on serum lipids. CONCLUSION: An HSF-SA diet results in weight loss after 6 weeks without adverse effects on serum lipid levels verified by nuclear magnetic resonance, and further weight loss with a lipid-neutral effect may persist for up to 52 weeks.

Results of use of metformin and replacement of starch with saturated fat in diets of patients with type 2 diabetes.

OBJECTIVE: To improve glycemic control by substituting saturated fat for starch, to identify any adverse effect on lipids masked by the extensive use of metformin and lipid-lowering drugs, and to attempt to separate dietary effects from effects of multiple drugs. METHODS: We undertook a retrospective review of medical records of patients who completed 1 year of follow-up after dietary prescription. The study subjects included 151 patients in the diet group (whose dietary instructions included high saturated fat but starch avoidance) and 132 historical control subjects (who were allowed unlimited monounsaturated fat but had restriction of starch in their diets). RESULTS: Hemoglobin A1c (HbA1c) levels improved in both study groups (-1.4 +/- 0.2% [P<0.001]; 95% confidence interval [CI], -1.9 to -0.9). Use of metformin was associated with a decrease in HbA1c (-0.12 +/- 0.003%/mo [P<0.001]; 95% CI, -0.17 to -0.07). The diet group had an additional decrease of -0.7 +/- 0.2% (P<0.001; 95% CI, -1.1 to -0.3). Weight increase was associated with the use of insulin (+0.3 +/- 0.07 kg/mo [P<0.001]; 95% CI, 0.2 to 0.5), sulfonylurea (+0.18 +/- 0.06 kg/mo [P<0.01]; 95% CI, 0.05 to 0.30), and troglitazone (+0.7 +/- 0.2 kg/mo [P<0.005]; 95% CI, 0.3 to 1.2). Although not statistically significant, metformin therapy showed a trend for weight loss (-0.14 +/- 0.08 kg/mo; P = 0.07). An additional weight loss was noted in the diet group (-2.65 +/- 0.62 kg [P<0.001]; 95% CI, -3.87 to -1.44). Hydroxymethylglutaryl-coenzyme A reductase inhibitor use was associated with reduced total cholesterol level (-1.7 +/- 0.6 mg/dL per month [P<0.005]; 95% CI, -2.9 to -0.5). The diet group had an additional decrease of -13.0 +/- 4.5 mg/dL (P<0.001; 95% CI, -21.9 to -4.1). No significant effect of the diet on triglyceride, low-density lipoprotein, or high-density lipoprotein levels was detected. CONCLUSION: Addition of saturated fat and removal of starch from a high-monounsaturated fat and starch-restricted diet improved glycemic control and were associated with weight loss without detectable adverse effects on serum lipids.