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Biomedical subjects

C C Shek

Publications and source records attributed to C C Shek.

At least 37 records · Page 2Linked to original sources
PubMed1997

Lithium pharmacokinetics in Chinese manic-depressive patients.

The pharmacokinetics of lithium was studied in 16 manic-depressive Chinese adults who were on lithium therapy in Hong Kong. A two-compartment open model was used to describe the plasma data obtained. The steady-state volume of distribution and total plasma clearance were estimated to be 63.4 +/- 38.3 L and 1.47 +/- 0.49 L/hr, respectively, which were similar to those reported in studies of Caucasian subjects. The lithium clearance was found to be significantly related to lean body mass (r = 0.646, p < 0.01) but not to either total body weight, age, or creatinine clearance. Interindividual variability in lithium clearance was substantially reduced to a coefficient of variation of 24.6% from 33.3% when lean body mass was considered. The combined plasma and urine data indicate that the rate and extent of lithium absorption were similar to those of earlier studies in Caucasian subjects on a standard lithium dosage.

Adult↗
PubMed1997

A partial dialysate collection method.

This study validates Ing's partial dialysate collection method, which employs proportionate collection using a side tube capped with a small-gauge plastic needle. The urea nitrogen and creatinine levels of the small representative fraction of spent dialysate collected in the above fashion are undistinguishable from those obtained from the total spent dialysate. The estimated urea nitrogen removed during hemodialysis using this approach is similar to that using the total dialysate collection method; Ing's method is simple and useful in quantifying the dialysis dosage and in its assessment of the nutritional status of patients on hemodialysis.

Bicarbonates↗
PubMed1995

Effects of fluvastatin on lipid profile and apolipoproteins in Chinese patients with hypercholesterolemia.

The effects of fluvastatin treatment on lipid profile and apolipoproteins were assessed in a group of 31 Chinese patients with hypercholesterolemia, maintained on a constant low-fat diet. Some patients had the additional cardiovascular risk factors of hypertension and non-insulin-dependent diabetes mellitus, and 6 patients had familial hypercholesterolemia. Baseline lipid levels were measured after a 4-week placebo period, and these were repeated after 4 weeks of treatment with fluvastatin 20 mg daily, and after 4 weeks of treatment with fluvastatin 40 mg daily. Total cholesterol, low density lipoprotein cholesterol, and apolipoprotein (apo) B were each reduced to the same extent with the 2 doses of fluvastatin (-20%, -26%, and -20%, respectively). Triglycerides and very low density lipoprotein cholesterol were also reduced by about 12% with the 2 doses of fluvastatin. Apo A-I was increased by 7% and high density lipoprotein cholesterol (HDL-C) was increased by 10% with the 40 mg dose. The increase in HDL-C was due to increases in both HDL2-C (18%) and HDL3-C (7%). Lipoprotein(a) levels did not show any significant change with the 2 doses of fluvastatin in this short-term study. One patient developed reversible asymptomatic elevation of liver enzymes with the higher dose of fluvastatin; otherwise the drug was well tolerated and no patients had to be withdrawn from the study.

Adult↗
PubMed1994

The prevalence of hypercalcaemia in pulmonary and miliary tuberculosis--a longitudinal study.

We studied the prevalence of hypercalcaemia in 34 Chinese patients with pulmonary (n = 32) or miliary (n = 2) tuberculosis. None of these subjects were given vitamin D or calcium supplements. Plasma calcium levels were measured at presentation and at 1- to 2-monthly intervals after treatment. During the 6-month study period, two patients (6%) developed hypercalcaemia (plasma calcium greater than 2.51 mmol/l), as compared to figures of 16% to 28% in the United States and India. By correcting the plasma calcium to a normal albumin, five (15%) of our patients were hypercalcaemic, as compared to a figure of 48% in Greece. Apart from variations in methodology, discrepancies in the reported prevalence of hypercalcaemia in tuberculosis may be due to differences in sun exposure, and vitamin D and calcium intake.

Adolescent↗
PubMed1993

Lithium-associated transient thyrotoxicosis in 4 Chinese women with autoimmune thyroiditis.

Four Chinese female patients who suffered from manic-depressive disorder and underlying autoimmune thyroiditis developed transient episodes of thyrotoxicosis during maintenance lithium therapy. Endocrinologically speaking, three of them had "Hashitoxicosis", while the other had silent lymphocytic thyroiditis. Albeit rare among Western patients, such lithium-associated thyroid dysfunctions appeared to be more likely to occur in Hong Kong Chinese. They seemed to involve multiple aetiological factors, such as autoimmune thyroid disease, the toxic and immunomodulatory roles of lithium and perhaps genetic and dietary factors. Because of their self-limiting nature, the importance of avoiding unnecessary and potentially deleterious antithyroid treatment is emphasised.

Adolescent↗
PubMed1993

17 alpha-Hydroxylase deficiency with persistence of müllerian ducts in a genotypic male and paradoxical aldosterone secretion.

We report a case of congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency in a Chinese genotypic male patient. Despite the male genotype, normal female external genitalia were present and with the introduction of cyclical oestrogen therapy withdrawal bleeding occurred, confirming the presence of functional endometrial tissue. We believe this to be the first report of persistent Mullerian duct structures in a genotypic male with 17 alpha-hydroxylase deficiency. It could be explained by either impaired secretion or impaired action of anti-Mullerian hormone. Further, contrary to the usual finding of suppressed aldosterone secretion, this patient had measurable levels of plasma aldosterone.

Adolescent↗
PubMed1992

Thyroid abnormalities during chronic lithium treatment in Hong Kong Chinese: a controlled study.

Fifty Chinese psychiatric patients on chronic lithium treatment and the same number of sex- and age-matched control outpatients were assessed by a thyroidologist and underwent laboratory investigations. Lithium patients had a higher rate of goitres (50% vs 10%, P < 0.0001) and a higher mean TSH level (P < 0.005) than controls. Thyroid antibodies were detected in 7 older manic-depressive patients as opposed to 1 control, but not in patients with recurrent unipolar mania. Five patients, but no controls, had single or multiple episodes of hyperthyroidism, which was followed in 2 of them by biochemical hypothyroidism. It is suggested that variations in iodine status, dietary goitrogens, immunogenetic makeup and their complex interactions with chronic lithium treatment may contribute to ethnically different patterns of thyroid abnormalities.

Adolescent↗
PubMed1992

Folate concentration in Chinese psychiatric outpatients on long-term lithium treatment.

Among 46 Chinese and mostly manic-depressive (85%) outpatients attending a lithium clinic in Hong Kong, virtually no patients had low serum (0%) or erythrocyte (2%) folate. Their mean folate levels did not differ from lithium-free outpatients. Although serum folate correlated negatively with lithium dose (P less than 0.002) and serum level (P less than 0.01), lithium treatment probably did not by itself cause low folate. Folate level was not related to diagnosis, duration of mental illness, other drug usage or spot affective morbidity. Patients with a good response to lithium in the previous one year had a higher mean serum folate level than those with unsatisfactory response (P less than 0.05). These data suggest that folate deficiency is uncommon among Chinese psychiatric outpatients, but support recent evidence that folate at high concentrations enhances lithium prophylaxis.

Ambulatory Care↗
PubMed1992

Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women.

OBJECTIVE: To study the age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of calcium metabolism in Chinese women who habitually have a low calcium intake. DESIGN: Cross-sectional study. SUBJECTS: One hundred and fifty-six healthy Chinese women aged 20-83 years. None were on any medication or vitamin supplements. Subjects over the age of 60 years were all living in a hostel; younger subjects were nurses or subjects attending a family clinic for minor illnesses. MEASUREMENTS: Fasting blood and urine samples were collected for biochemical measurements and calcium absorption was measured using 45Ca by the method of Marshall and Nordin. Bone density was measured by dual energy X-ray densitometry (Norland X R20 X-ray bone densitometer) at the left hip and lumbar spine. Serum parathyroid hormone was measured by a chemiluminometric assay. RESULTS: Plasma ionized calcium concentration, alkaline phosphatase, bicarbonate, plasma creatinine and serum B2 microglobulin were significantly higher in the elderly than in the young, whereas plasma phosphate and the anion gap were higher in the young. Urinary excretion of calcium, phosphate and hydroxyproline were all higher in older women. Plasma parathyroid hormone concentration was positively correlated with age even after taking into account the decline in renal function (as indicated by the rise in B2 microglobulin (r = 0.506, P less than 0.001). Serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were not lower in the older women. Fractional calcium absorption from an oral load of radiolabelled calcium was significantly lower in the older women and 37% of the older women were below the 2.5 percentile found in the younger women. Bone density measured by dual energy X-ray densitometry was also significantly lower in the elderly. CONCLUSION: In Chinese women there is an increase in PTH and a decrease in calcium absorption with age in spite of the presence of normal vitamin D metabolites.

Absorption↗
PubMed1992

Hypercalcemia in active pulmonary tuberculosis and its occurrence in relation to the radiographic extent of disease.

The prevalence of hypercalcemia in tuberculosis in Hong Kong and its occurrence in relation to the radiographic extent of disease were studied in 57 patients with sputum smear (n = 44) and/or culture positive (n = 13) pulmonary tuberculosis and in five patients with military tuberculosis prior to treatment. Only one (1.6%) patient had a corrected plasma calcium level above the reference range for our laboratory. There was a positive relationship between the corrected plasma calcium levels and the radiographic extent of disease (r = 0.37), p < 0.01). As the occurrence of hypercalcemia in tuberculosis is known to be influenced by the calcium intake, our finding of a low prevalence of "absolute" hypercalcemia in Hong Kong could be related to the low dietary calcium intake in these subjects.

Adult↗
PubMed1991

Nephrogenous cyclic AMP in primary hepatocellular carcinoma patients with or without hypercalcaemia.

OBJECTIVE: To study the relationship between the excretion of nephrogenous cyclic AMP (NcAMP) and other blood and urine parameters as an index of PTH-like activity in patients with primary hepatocellular carcinoma. DESIGN: After overnight fast, a double voided urine and a blood sample were collected from each subject for determination of various analytes and results compared between various groups. PATIENTS: Fifty-five consecutive untreated patients with primary hepatocellular carcinoma, 14 healthy controls and eight patients with cirrhosis only. MEASUREMENTS: Serum calcium, phosphate, alkaline phosphatase, albumin, creatinine and urinary calcium, creatinine and hydroxyproline were measured by routine methods. cAMP was measured in plasma and urine by a radioimmunoassay (Diagnostic Products Corporation) and PTH measured in serum by an immunoradiometric assay (Nichols Institute). TmP/GFR, NcAMP etc. were calculated according to various published methods. RESULTS: Four out of 55 patients (7%) with primary hepatocellular carcinoma had hypercalcaemia. These four patients had significantly lower (P less than 0.05) phosphate, PTH and TmP/GFR and elevated NcAMP (P less than 0.001) compared with normocalcaemic hepatocellular carcinoma and cirrhotic patients, and healthy controls. The excretion of hydroxyproline and calcium was significantly elevated (P less than 0.001) in the hypercalcaemic patients. Bone resorption was found to be the major cause of hypercalcaemia in three of the four hypercalcaemic patients. Fifteen hepatocellular carcinoma patients (29%) with normocalcaemia had suppressed PTH. CONCLUSION: We conclude that a PTH-like humoral factor such as PTH related peptide is the cause of hypercalcaemia in patients with primary hepatocellular carcinoma, and that in some normocalcaemic patients with this tumour PTH is suppressed.

Adult↗
PubMed1991

Hyponatremia in a hospital population.

The frequency, causes, and outcome of hyponatremia (plasma sodium less than 125 mmol/L), and the value of some routine investigations were studied during a six month period in a hospital population. The incidence and prevalence of hyponatremia were 1.5 and 2.6 per 100 patients per day, respectively. A majority of patients (75%) developed hyponatremia in the hospital. The commonest cause of hyponatremia was normovolemic hyponatremia (79 patients). Hypovolemic and hypervolemic hyponatremia were seen in 63 and 21 patients, respectively. Urine osmolality did not differ between the three groups, and was of little diagnostic value. The mortality in the hyponatremic patients was 41.7%.

Adolescent↗
PubMed1990

Incidence, causes and mechanism of hypercalcaemia in a hospital population in Hong Kong.

To determine the incidence and causes of hypercalcaemia in a hospital population in Hong Kong, all 29,107 samples received in the laboratory in one year were analysed for plasma calcium and albumin, and samples with a plasma calcium concentration adjusted for albumin greater than 2.55 mmol/l were investigated. Plasma calcium greater than 2.55 mmol/l was found in 462 patients. Repeat samples were received from 302 of these and hypercalcaemia was confirmed in 183. The main causes of hypercalcaemia were malignancy (72.1 per cent), tuberculosis (6.0 per cent), and primary hyperparathyroidism (5.5 per cent). In the malignant hypercalcaemia group, carcinoma of lung was the most common (31.8 per cent) and carcinoma of breast was uncommon (3.0 per cent). Secondary deposits in bone were detected in 35 of the 122 solid tumours. In order to identify the mechanism of hypercalcaemia the contributions of renal tubular reabsorption and increased bone resorption to the plasma calcium concentration were calculated. Increased tubular reabsorption was the main contributor to hypercalcaemia in primary hyperparathyroidism and carcinoma of liver (none of whom had bony metastases) and it contributed significantly to hypercalcaemia in carcinoma of lung without bony metastases and carcinoma of oesophagus. We conclude that in Hong Kong (a) primary hyperparathyroidism is uncommon, (b) tuberculosis is an important cause and (c) humoral factors may be responsible for a relatively high proportion of cases of malignant hypercalcaemia.

Aged↗
PubMed1990

A cost effective approach to the biochemical diagnosis of iron deficiency.

Serum iron, total iron binding capacity (TIBC) and serum ferritin were measured on 419 samples to evaluate the value of these measurements and to develop a cost effective strategy for diagnosis of iron deficiency. If transferrin saturation (PS) of less than 16% and TIBC of greater than 70 mumol/L were used as diagnostic criteria for iron deficiency, 93% of the 59 patients who fulfilled these criteria were iron deficient; 49 had low serum ferritin and six were iron deficient with normal serum ferritin levels. When we used PS of greater than or equal to 22% and TIBC less than or equal to 70 mumol/L to exclude iron deficiency, 99% of those patients who fulfilled these criteria had normal serum ferritin levels. We, therefore, suggest that for biochemical diagnosis of iron deficiency serum iron and TIBC should be done first, and serum ferritin is not required when the PS is less than 16% and TIBC greater than 70 mumol/l or if PS is greater than or equal to 22% and TIBC less than or equal to 70 mumol/L. In all other cases serum ferritin is measured to detect iron deficiency. This approach will save 35 to 40% of reagent costs.

Anemia, Hypochromic↗
PubMed1988

Vitamin A and E status in healthy elderly Chinese in Hong Kong.

Daily intakes of retinol and beta-carotene equivalents, plasma retinol, retinol binding protein and plasma vitamin E were estimated in a cluster sample of apparently healthy elderly subjects aged 60 years and over in Hong Kong leading an active life in the community. Intakes were available from 418 and plasma measurements from 385 subjects. There were no age or sex differences in intakes. Plasma retinol and retinol binding protein levels showed no sex- or age-related difference, while plasma vitamin E levels were higher in women. Retinol binding protein, plasma retinol and plasma vitamin E levels were comparable to published values for Chinese and Caucasians of all ages. Vitamin A and E status appears to be adequate in this elderly Chinese population.

Aged↗