Central serous chorioretinopathy secondary to intramuscular testosterone therapy

Summary

A patient treated with intramuscular testosterone replacement therapy for primary hypogonadism developed blurred vision shortly after receiving his testosterone injection. The symptom resolved over subsequent weeks and recurred after his next injection. A diagnosis of central serous chorioretinopathy (CSR) was confirmed following ophthalmology review. A decision was made to change the patient's testosterone regime from this 12-weekly intramuscular injection to a daily topical testosterone gel, given the possibility that peak blood levels of testosterone following intramuscular injection were causing his ocular complaint. His CSR did not recur after this change in treatment. CSR secondary to testosterone therapy is a rare finding but has been reported previously in the literature.

Learning Points

Blurred vision in patients treated with testosterone replacement therapy (TRT) should prompt an ophthalmology review. The potential for reduced risk of central serous chorioretinopathy (CSR) with daily transdermal testosterone remains a matter of conjecture. CSR is a rare potential side effect of TRT.

The incidence of anterior pituitary hormone deficiencies in patients with microprolactinoma and idiopathic hyperprolactinaemia

INTRODUCTION

Patients with microprolactinoma and idiopathic hyperprolactinaemia are not generally considered to be at risk of hypopituitarism and are therefore not routinely screened for this abnormality. In our clinical practice, we have observed a number of patients with nonmacroadenomatous hyperprolactinaemia to have anterior pituitary hormone deficits.

AIMS

We aimed to establish the frequency and clinical significance of anterior pituitary hormone deficiencies, comparing patients with radiologically proven microprolactinomas and patients with idiopathic hyperprolactinaemia.

STUDY DESIGN

We retrospectively examined the casenotes of 206 patients with hyperprolactinaemia from our centre. Patients who did not fit the profile of surgically naïve microprolactinoma or idiopathic hyperprolactinaemia or who had incomplete data were excluded, resulting in a study group of 56 patients.

RESULTS

A total of 35 patients with MRI evidence of microprolactinoma were identified, three (8.57%) of whom had one or more anterior pituitary hormone deficiencies. A total of 21 patients with MRI-negative idiopathic hyperprolactinaemia were identified, nine (42%) of whom had one or more anterior pituitary hormone deficiencies (P<.01). Only one patient in the MRI-positive group had deficiency that required hormone replacement, in contrast six patients in the MRI-negative group had deficiencies that were of clinical significance and which required hormone replacement.

SUMMARY

This study shows a clinically significant incidence of anterior pituitary hormone deficiency in patients with idiopathic hyperprolactinaemia. The authors recommend that dynamic pituitary assessment should be considered routinely in this patient group. A prospective study would be required to assess the underlying cause for these abnormalities, as they suggest a nontumour pan-pituitary process.

Pituitary tuberculoma: a rare cause of sellar mass

INTRODUCTION

Pituitary tuberculosis is an uncommon cause of sellar mass [1]; the estimated prevalence worldwide is not known, and there have been no reports of the condition occurring in Ireland. Tuberculosis of the pituitary gland may present as a sellar mass or with symptoms of hypopituitarism.

CASE PRESENTATION

A 41-year-old woman, with a short prodromal history without endocrine symptoms, was found to have pituitary tuberculosis after the demonstration of a sellar mass on MRI, and lumbar puncture findings consistent with lymphocytic meningitis.

CONCLUSION

To our knowledge, this is the first published case of pituitary tuberculoma in Ireland.

Heterogenous patterns of recovery of thirst in adult patients with adipsic diabetes insipidus

BACKGROUND

The natural history of adipsic diabetes insipidus (ADI) is not well described, and reports of recovery of thirst are rare.

DESIGN AND METHODS

Case histories presentation. ADI was identified by demonstrating absent thirst and arginine vasopressin (AVP) responses to hypertonic saline infusion.

RESULTS

Twelve patients with ADI were identified (craniopharyngioma 5, anterior communicating artery aneurysm (ACOM) repair 4, congenital 1, neurosarcoidosis 1, prolactinoma 1). Three patients died. Six patients had permanent ADI. Three patients had recovery of thirst, with a heterogenous pattern of recovery. In the first case, ADI had developed after clipping of an ACOM aneurysm. Ten years after surgery; he sensed the return of thirst; repeated hypertonic saline infusion showed recovery of thirst and AVP secretion. In the second case, a 41-year-old female with an intrasellar craniopharyngioma developed post-operative ADI with persistent hypernatremia. Two years post-operatively, she complained of thirst, and hypertonic saline infusion showed normalization of thirst but absent AVP responses, confirming recovery of thirst, but with persistent diabetes insipidus (DI). In the third case, a 29-year-old Caucasian had craniotomy and radiotherapy for craniopharyngioma and developed ADI post-operatively. Eight years post-op, she presented with thirst, seizures and pNa of 112 mmol/l. Hypertonic saline infusion showed persistent DI but thirst responses typical of compulsive water drinking; she has had recurrent hyponatraemia since then.

CONCLUSIONS

We report that 3/12 patients with ADI recovered thirst after longstanding adipsia with heterogenous pattern of recovery. Both the mortality of 25% and the recovery rate of 25% should be considered when planning long-term surveillance.

Musculoskeletal Health, Kidney and Liver Function in Retired Jockeys

The long-term implications of making-weight daily on musculoskeletal health and functioning of the kidney and liver remain unknown. This study aimed to investigate musculoskeletal health and kidney and liver function in a group of retired jockeys. 28 retired male jockeys (age 50-70 years) provided fasting blood samples for markers of bone metabolism and kidney and liver function. A dual-energy x-ray absorptiometry (DXA) scan was performed for the assessment of bone mineral density (BMD). Established reference ranges were used for interpretation of results. Comparisons were made between retired jockeys based on the professional racing licence held: Flat, National Hunt or Dual. Mean whole-body osteopenia was reported, with no differences between groups. Bone markers, micronutrients, electrolytes and associated hormones, and markers for kidney and liver function were within clinical normative ranges. No differences existed between groups. Results indicate the retired jockeys in this study do not demonstrate compromised bone health or kidney and liver function. However, the retired jockeys may not have undergone chronic weight cycling in the extreme manner evident in present-day jockeys, indicating the next generation of jockeys may face more of a problem. Jockeys should be tracked longitudinally throughout their racing career and beyond.

Abnormal plasma sodium concentrations in patients treated with desmopressin for cranial diabetes insipidus: results of a long-term retrospective study

CONTEXT AND OBJECTIVE

Patients with cranial diabetes insipidus (CDI) are at risk of developing both hypernatraemia and hyponatraemia, due to the condition itself or secondary to treatment with vasopressin-analogues or during administration of i.v. fluids. We aimed to assess the frequency and impact of dysnatraemias in the inpatient (INPT) and outpatient (OPT) setting in desmopressin-treated CDI, comparing those with normal thirst with those with abnormal thirst.

DESIGN

The study included 192 patients with cranial diabetes, who were identified from the Beaumont Pituitary Database, a tertiary referral centre. Retrospective case note audit was performed and the clinical and biochemical information of 147 patients with CDI were available for analysis.

RESULTS

A total of 4142 plasma sodium measurements for 137 patients with normal thirst, and 385 plasma sodium measurements for ten patients with abnormal thirst were analysed. In those with normal thirst, the most common OPT abnormality was mild hyponatraemia (pNa(+) 131-134  mmol/l) in 27%, while 14.6% had more significant hyponatraemia (pNa(+) ≤130  mmol/l). Of those patients with normal thirst, 5.8% were admitted due to complications directly related to hyponatraemia. Compared with patients with normal thirst, those with abnormal thirst were more likely to develop significant OPT hypernatraemia (20% vs 1.4%, P=0.02) and significant INPT hyponatraemia (50% vs 11.1%, P 0.02).

CONCLUSION

OPT management of CDI is complicated by a significant incidence of hyponatraemia. In contrast, OPT hypernatraemia is almost exclusively a complication seen in adipsic CDI, who also had more frequent INPT hyponatraemia. CDI associated with thirst disorder requires increased physician attention and patient awareness of potential complications.

Chronic hypopituitarism is uncommon in survivors of aneurysmal subarachnoid haemorrhage

OBJECTIVE

The incidence of hypopituitarism after aneurysmal subarachnoid haemorrhage (SAH) is unclear from the conflicting reports in the literature. As routine neuroendocrine screening for hypopituitarism for all patients would be costly and logistically difficult, there is a need for precise data on the frequency of hypopituitarism and on factors which might predict the later development of pituitary dysfunction. We aimed to: (i) Establish the incidence of long-term hypopituitarism in patients with aneurysmal SAH. (ii) Determine whether data from patients' acute admission with SAH could predict the occurrence of long-term hypopituitarism.

DESIGN

One hundred patients were studied prospectively from the time of presentation with acute SAH. Plasma cortisol, plasma sodium and a variety of clinical and haemodynamic parameters were sequentially measured for the first 12 days of their acute admission. Forty-one patients then underwent dynamic pituitary testing at median 15 months following SAH (range 7-30 months), with insulin tolerance test (ITT) or, if contraindicated, a glucagon stimulation test (GST) plus short synacthen test (SST). If symptoms of cranial diabetes insipidus (CDI) were present, a water deprivation test was also performed.

RESULTS

Forty-one patients attended for follow-up dynamic pituitary testing. Although 14 of 100 had acute glucocorticoid deficiency immediately following SAH, only two of 41 had long-term adrenocorticotrophic hormone (ACTH) deficiency and four of 41 had growth hormone (GH) deficiency. None were hypothyroid or gonadotrophin deficient. None had chronic CDI or hyponatraemia. There was no association between acute glucocorticoid deficiency, acute CDI or acute hyponatraemia and long-term pituitary dysfunction.

CONCLUSION

Both anterior and posterior hypopituitarism are very uncommon following SAH and are not predicted by acute clinical, haemodynamic or endocrinological parameters. Routine neuroendocrine screening is not justified in SAH patients.

Hyponatremia following mild/moderate subarachnoid hemorrhage is due to SIAD and glucocorticoid deficiency and not cerebral salt wasting

CONTEXT

Hyponatremia is common after acute subarachnoid hemorrhage (SAH) but the etiology is unclear and there is a paucity of prospective data in the field. The cause of hyponatremia is variously attributed to the syndrome of inappropriate antidiuresis (SIAD), acute glucocorticoid insufficiency, and the cerebral salt wasting syndrome (CSWS).

OBJECTIVE

The objective was to prospectively determine the etiology of hyponatremia after SAH using sequential clinical examination and biochemical measurement of plasma cortisol, arginine vasopressin (AVP), and brain natriuretic peptide (BNP).

DESIGN

This was a prospective cohort study.

SETTING

The setting was the National Neurosurgery Centre in a tertiary referral centre in Dublin, Ireland.

PATIENTS

One hundred patients with acute nontraumatic aneurysmal SAH were recruited on presentation.

INTERVENTIONS

Clinical examination and basic biochemical evaluation were performed daily. Plasma cortisol at 0900 hours, AVP, and BNP concentrations were measured on days 1, 2, 3, 4, 6, 8, 10, and 12 following SAH. Those with 0900 hours plasma cortisol<300 nmol/L were empirically treated with iv hydrocortisone.

MAIN OUTCOME MEASURES

Plasma sodium concentration was recorded daily along with a variety of clinical and biochemical criteria. The cause of hyponatremia was determined clinically. Later measurement of plasma AVP and BNP concentrations enabled a firm biochemical diagnosis of the cause of hyponatremia to be made.

RESULTS

Forty-nine of 100 developed hyponatremia<135 mmol/L, including 14/100<130 mmol/L. The cause of hyponatremia, and determined by both clinical examination and biochemical hormone measurement, was SIAD in 36/49 (71.4%), acute glucocorticoid insufficiency in 4/49 (8.2%), incorrect iv fluids in 5/49 (10.2%), and hypovolemia in 5/49 (10.2%). There were no cases of CSWS.

CONCLUSIONS

The most common cause of hyponatremia after acute nontraumatic aneurysmal SAH is SIAD. Acute glucocorticoid insufficiency accounts for a small but significant number of cases. We found no cases of CSWS.

Acute glucocorticoid deficiency and diabetes insipidus are common after acute traumatic brain injury and predict mortality

CONTEXT

Published data demonstrates that hypopituitarism is common after traumatic brain injury (TBI). Hormone deficiencies are transient in many, but the natural history of the acute changes after TBI has not been documented. In addition, it is not clear whether there are any early parameters that accurately predict the development of permanent hypopituitarism.

OBJECTIVES

There were 3 main objectives of this study: 1) to describe the natural history of plasma cortisol (PC) changes and sodium balance after TBI; 2) to identify whether acute hypocortisolemia or cranial diabetes insipidus (CDI) predict mortality; and 3) to identify whether the acute pituitary dysfunction predicts the development of chronic anterior hypopituitarism.

DESIGN

Each TBI patient underwent sequential measurement of PC, plasma sodium, urine osmolality, and fluid balance after TBI. All other anterior pituitary hormones were measured on day 10 after TBI. The results from 15 surgical comparisons defined a PC less than 300 nmol/L as inappropriately low for an acutely ill patient. CDI was diagnosed according to standard criteria. Surviving TBI patients underwent dynamic anterior pituitary testing at least 6 months after TBI.

SETTING

The patients were recruited from the Irish National Neurosurgery Centre.

PATIENTS

One hundred sequential TBI patients were recruited. Fifteen patients admitted to Intensive Therapy Unit (ITU) after major surgery were recruited as comparison patients.

MAIN OUTCOME MEASURES

PC in TBI patients was compared with that of comparison patients. The mortality rate was compared between TBI patients with and without acute hypocortisolemia. Results of follow-up dynamic pituitary testing were compared between those with and without acute hypocortisolemia.

RESULTS

Most of the TBI patients (78%) developed inappropriately low PC after TBI. Low PC and CDI were predictive of mortality. Thirty-nine percent of the patients who had follow-up testing had at least 1 pituitary hormone deficit, all of whom had had previous acute hypocortisolemia or CDI.

CONCLUSIONS

Acute hypocortisolemia and CDI are predictive of mortality and long-term pituitary deficits in TBI.

Incidence and pathophysiology of severe hyponatraemia in neurosurgical patients

BACKGROUND

Hyponatraemia is a well-recognised complication of neurosurgical conditions, but the incidence and implications have not been well documented.

OBJECTIVE

To define the incidence, pathophysiology and clinical implications of significant hyponatraemia in several neurosurgical conditions.

METHODS

All patients admitted to the Irish National Neurosciences Centre at Beaumont Hospital, Dublin with traumatic brain injury, subarachnoid haemorrhage, intracranial neoplasm, pituitary disorders and spinal disorders who developed significant hyponatraemia (plasma sodium <130 mmol/l) from January 2002 to September 2003 were identified from computerised laboratory records. Data were collected by retrospective case note analysis.

RESULTS

Hyponatraemia was more common in patients with pituitary disorders (5/81, 6.25%; p = 0.004), traumatic brain injury (44/457, 9.6%; p<0.001), intracranial neoplasm (56/355, 15.8%; p<0.001) and subarachnoid haemorrhage (62/316, 19.6%; p<0.001) than in those with spinal disorders (4/489, 0.81%). The pathophysiology of hyponatraemia was: syndrome of inappropriate antidiuretic hormone secretion (SIADH) in 116 cases (62%) (31 (16.6%) drug-associated), hypovolaemic hyponatraemia in 50 cases (26.7%) (which included patients with insufficient data to assign to the cerebral salt-wasting group (CSWS)), CSWS in nine cases (4.8%), intravenous fluids in seven cases (3.7%) and mixed SIADH/CSWS in five cases (2.7%). Hyponatraemic patients with cerebral irritation had significantly lower plasma sodium concentrations (mean (SD) 124.8 (0.34) mmol/l) than asymptomatic patients (126.6 (0.29) mmol/l) (p<0.0001). Hyponatraemic patients had a significantly longer hospital stay (median 19 days (interquartile range (IQR) 12-28)) than normonatraemic patients (median 12 days (IQR 10.5-15)) (p<0.001).

CONCLUSIONS

Hyponatraemia is common in intracerebral disorders and is associated with a longer hospital stay. Cerebral irritation is associated with more severe hyponatraemia. SIADH is the most common cause of hyponatraemia and is often drug-associated.

Prevalence of the metabolic syndrome in patients with diabetes mellitus

BACKGROUND

Metabolic syndrome (MetS) is a vascular risk factor with prevalence in the general population of 17-25%.

AIM

To determine the prevalence of MetS in patients with diabetes mellitus (DM).

METHODS

A total of 200 patients [18% type 1 (T1DM), 82% type 2 (T2DM)] attending for annual review were studied. Standard blood tests were requested. Blood pressure and waist circumference were measured. Adult Treatment Panel III (ATP III) criteria for diagnosis of MetS were applied.

RESULTS

A total of 122 (61%) patients had MetS. More patients with T2DM (69.5%) than TIDM (22.2%) had MetS. Despite treatment of DM (100%), hypertension (69.5%) and dyslipidaemia (48.3%), 114 patients (57%) still met the criteria for MetS at time of study.

CONCLUSIONS

Most T2DM patients have MetS but it is uncommon in T1DM. Despite treatment, almost half of patients still met the criteria for MetS. Aggressive treatment of MetS components is required to reduce cardiovascular risk in DM.

An apparent phaeochromocytoma and abnormal thyroid function tests

A 41-year-old lady presented with classical symptoms of a phaeochromocytoma and markedly elevated urinary adrenaline concentration. Urinary fractionated metanephrine and normetanephrine concentrations were within the normal reference range. Computed tomography of the abdomen/pelvis and I123 meta-iodobenzylguanidine scans were negative. Factitious adrenaline use was established as the diagnosis.

Elevated plasma concentrations of atrial and brain natriuretic peptide in type 1 diabetic subjects

BACKGROUND

The intravenous infusion of atrial (ANP) and brain (BNP) natriuretic peptides have been shown to increase urinary albumin excretion in type 1 diabetes.

AIMS

To measure plasma ANP and BNP concentrations in patients with type 1 diabetes and to examine the parameters associated with elevated plasma concentrations. Methods We measured plasma ANP and BNP concentrations, UAER, HbA1C systolic blood pressure, and left ventricular mass index. Plasma ANP and BNP were also measured in non-diabetic control subjects for comparison.

RESULTS

Using multivariate regression analysis plasma ANP correlated positively with HbA1C (1.9 + 0.47, p = 0.0002), UAER (0.37 + 0.05, p = 0.00001), SBP (1.26 + 0.5, p = 0.01) and LVMI (00.46 + 0.25, p = 0.07). BNP was positively related with LVMI (0.95 + 0.4, p = 0.02), and UAER (0.56 + 0.08, p = 0.001).

CONCLUSIONS

Plasma concentrations of ANP and BNP are elevated in some patients with type 1 diabetes. Plasma ANP concentrations are closely related to UAER and elevated plasma concentrations are associated with poor glycaemic control and systemic hypertension. Plasma BNP concentration is related to LVMI.

Downward resetting of the osmotic threshold for thirst in patients with SIADH

The syndrome of inappropriate antidiuretic hormone (SIADH) is characterized by euvolemic hyponatremia. Patients with SIADH continue to drink normal amounts of fluid, despite plasma osmolalities well below the physiological osmotic threshold for onset of thirst. The regulation of thirst has not been previously studied in SIADH. We studied the characteristics of osmotically stimulated thirst and arginine vasopressin (AVP) secretion in eight subjects with SIADH and eight healthy controls and the nonosmotic suppression of thirst and AVP during drinking in the same subjects. Subjects underwent a 2-h infusion of hypertonic (855 mmol/l) NaCl solution, followed by 30 min of free access to water. Thirst rose significantly in both SIADH (1.5 +/- 0.6 to 8.0 +/- 1.2 cm, P < 0.0001) and controls (1.8 +/- 0.8 to 8.4 +/- 1.5 cm, P < 0.0001), but the osmotic threshold for thirst was lower in SIADH (264 +/- 5.5 vs. 285.9 +/- 2.8 mosmol/kgH(2)O, P < 0.0001). SIADH subjects drank volumes of water similar to controls after cessation of the infusion (948.8 +/- 207.6 vs. 1,091 +/- 184 ml, P = 0.23). The act of drinking suppressed thirst in both SIADH and controls but did not suppress plasma AVP concentrations in SIADH compared with controls (P = 0.007). We conclude that there is downward resetting of the osmotic threshold for thirst in SIADH but that thirst responds to osmotic stimulation and is suppressed by drinking around the lowered set point. In addition, we demonstrated that drinking does not completely suppress plasma AVP in SIADH.

Abnormal regulation of thirst and vasopressin secretion following surgery for craniopharyngioma

OBJECTIVE

In this study we aimed to establish the frequency of postoperative diabetes insipidus and the incidence and characteristics of abnormalities of thirst in a cohort of patients with craniopharyngioma, in whom neurosurgery had been performed.

DESIGN

Diabetes insipidus was determined by either standard criteria for diagnosis in the immediate postoperative period, or by water deprivation test, in all craniopharyngioma and pituitary tumour patients who underwent surgery in Beaumont Hospital between the years 1986 and 1998. Osmoregulated thirst and vasopressin release were studied during a 2-h infusion of hypertonic (5%) saline followed by a 30-min period of free access to water.

PATIENTS

Data on the incidence of postoperative diabetes insipidus was collected in 26 patients with craniopharyngioma and 154 patients with pituitary adenomata. We recruited 16 healthy control patients, 16 patients with cranial diabetes insipidus following pituitary tumour surgery and 16 patients with cranial diabetes insipidus following craniopharyngioma resection for the hypertonic saline infusion study.

RESULTS

Twenty-five patients out of 26 (96%) patients developed diabetes insipidus after surgery for craniopharyngioma, a much higher incidence than after surgery for suprasellar (26/88, 30%, P < 0.001) or intrasellar pituitary tumours (9/66, 14%, P < 0.001). Hypertonic saline infusion identified abnormal thirst responses in five of the 16 craniopharygioma patients studied; all of the pituitary tumour patients had a normal thirst response. Three of the craniopharyngioma patients had adipsic diabetes insipidus whilst two had polydipsic diabetes insipidus.

CONCLUSION

This study demonstrates following surgery for craniopharyngioma there is a high incidence of cranial diabetes insipidus and a significant incidence of abnormal thirst responses to osmotic stimuli.

Baroregulation of vasopressin release in adipsic diabetes insipidus

Adipsic diabetes insipidus (ADI) occurs in association with a heterogeneous group of conditions. We report vasopressin (AVP) responses to hypotension in nine patients with ADI and nine controls. Hypertonic saline infusion produced absent thirst (1.7 +/- 1.7 to 1.5 +/- 1.7 cm, P = 0.99) and AVP responses (0.3 +/- 0.1 to 0.4 +/- 0.1 pmol/liter, P = 0.99) in the ADI group, who also drank less than the control group (258 +/- 200 ml vs. 1544 +/- 306 ml, P < 0.001). Intravenous infusion of trimetaphan camsylate produced a fall in mean arterial pressure of 31.6% +/- 8.9% in patients and 29.4% +/- 6.1% in controls. Plasma AVP concentrations rose from 1.4 +/- 0.8 to 340.3 +/- 497.4 pmol/liter (P < 0.001) in the control group. In three patients with craniopharyngioma, there was no rise in plasma AVP concentrations (0.3 +/- 0.1 to 0.3 +/- 0.1 pmol/liter, P = 0.96), but plasma AVP rose significantly in response to hypotension in the other six patients (0.4 +/- 0.2 to 204.5 +/- 223.2 pmol/liter, P < 0.001). We concluded that the AVP responses to hypotension in ADI are heterogeneous and reflect the site of the lesion causing the diabetes insipidus.

Brain natriuretic peptide increases urinary albumin and alpha-1 microglobulin excretion in Type 1 diabetes mellitus

Atrial natriuretic peptide (ANP) increases urinary albumin excretion in Type 1 diabetes mellitus (DM). Brain natriuretic peptide (BNP) is structurally and functionally related to ANP, but its effect on urine albumin excretion rate (UAER) is unknown.

AIMS

To compare the albuminuric effects of intravenous infusion of ANP and BNP, and to assess the effect of both peptides on tubular protein excretion.

METHODS

Eight subjects with Type 1 DM were randomised to a three leg, double blind, and placebo controlled study. On each study day, subjects were euglycaemic clamped and subsequently water loaded (20 mL/kg orally, plus urine losses) to steady state diuresis. When in steady state, creatinine clearance was estimated in three separate 1 hour periods. At the end of the first period, a 1 hour intravenous infusion of either placebo, ANP 0.025 microg/kg/min, or BNP 0.025 microg/kg/min was administered. There followed a 1 hour recovery period. Urine was collected at 15 min intervals for estimation of urine albumin (ACR) and alpha1 microglobulin creatinine ratio (MCR). Results were analysed by anova.

RESULTS

Creatinine clearance was similar on the three study days, and was unaltered by any infusion. ACR was unaltered by placebo (1.3 +/- 0.5-1.2 +/- 0.4 mg/mmol, mean +/- SD, p = 0.81), but increased compared to placebo with infusion of both ANP (1.2 +/- 0.4-9.8 +/- 8.4 mg/mmol, P = 0.0004), and BNP (1.1 +/- 0.4-13.4 +/- 8.6 mg/mmol, P = 0.0001). The MCR was unaltered by placebo infusion (P = 0.89), but increased compared with placebo after infusion of ANP (5.4 +/- 0.9-12.3 +/- 4.2 mg/mmol, P < 0.0001), and BNP (5.4 +/- 0.8-12.1 +/- 2.5 mg/mmol, P < 0.0001).

CONCLUSIONS

Intravenous infusion of BNP and ANP both increase the urine excretion of albumin and the tubular protein alpha1 microglobulin, independent of creatinine clearance.

Acute hyperglycaemia causes elevation in plasma atrial natriuretic peptide concentrations in Type 1 diabetes mellitus

AIMS

To examine the effect of acute hyperglycaemia on atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations in Type 1 diabetes.

METHODS

The study was two limb, randomized, and single-blind. Eight Type 1 diabetes subjects were clamped at euglycaemia by intravenous infusion of insulin. When euglycaemia was established, the insulin infusion rate was left unaltered for the remainder of the protocol, and an intravenous infusion of either 500 ml 0.9% saline or 500 ml 10% dextrose was administered over 1 h. Blood was collected for estimation of plasma glucose, ANP and BNP concentrations at 30 min intervals for 2 h from the start of the infusion period. One week later, each subject received the alternate infusion. Results are expressed as mean +/- standard deviation, and were analysed by ANOVA.

RESULTS

Baseline plasma glucose (P = 0.8), ANP (P = 0.8) and BNP (P = 0.8) concentrations were similar on the study days. Plasma glucose rose with dextrose (6.1 + 0.5-15.1 + 2.8 mmol/l, P = 0.9). Plasma ANP concentrations were unaltered by saline infusion (76.5 +/- 14.7-77.7 +/- 15.2 pg/ml, P = 0.9), but increased with dextrose infusion (79 +/- 14-134 +/- 17.1 pg/ml, P < 0.0001), and were higher with dextrose than saline infusion (P < 0.0001). Plasma concentrations of BNP were not significantly altered by infusion of either dextrose (5.1 +/- 3.9-9.3 +/- 5.4 pg/ml, P = 0.63) or saline (4.3 +/- 3.5-6 +/- 5.2 pg/ml, P = 0.84).

CONCLUSIONS

Plasma concentrations of ANP, but not BNP, rise in response to acute hyperglycaemia in Type 1 diabetes.

Screening of patients with iron overload to identify hemochromatosis and porphyria cutanea tarda

OBJECTIVE

To assess the importance of iron overload as a risk factor for porphyria cutanea tarda (PCT).

DESIGN

Prospective study during a 4-month period.

SETTING

Departments of emergency care, gastroenterology, and dermatology in a tertiary referral center.

PATIENTS

Patients were deemed eligible for inclusion in the study if serum ferritin levels were greater than 500 micrograms/L (normal range: females, < 125 micrograms/L; males, < 325 micrograms/L).

MAIN OUTCOME MEASURES

Porphyrin excretion profiles were analyzed on all patients included in the study, where clinically relevant. A diagnosis of PCT was confirmed biochemically in all cases. The HLA typing was then performed on newly diagnosed cases of PCT.

RESULTS

Of 4127 patients tested, 240 patients with an elevated serum ferritin level were identified, of whom 74 had an elevated serum ferritin level of more than 500 micrograms/L. Of the latter group, 17.5% had hemochromatosis and 6.7% had PCT. The incidence of PCT in the hemochromatosis group was 23%; HLA typing revealed the presence of at least 1 of the hemochromatosis markers.

CONCLUSIONS

A high serum ferritin level in the absence of evident cause should prompt investigation for both hemochromatosis and PCT. The HLA heterozygosity for hemochromatosis in some patients with PCT may be a cause of hepatic siderosis.

Laparoscopic cholecystectomy: haemodynamic and neuroendocrine responses after pneumoperitoneum and changes in position

We have assessed the potential for myocardial ischaemia during laparoscopic cholecystectomy in 16 otherwise healthy patients. Continuous ambulatory ECG monitoring was commenced 12 h before operation and continued for 24 h after operation. The neuroendocrine stress response was assessed by measuring plasma concentrations of adrenaline and noradrenaline, human growth hormone, cortisol, renin and aldosterone, and prolactin, at specified times during surgery. Acute ST segment changes in the ECG occurred in only two patients. These episodes were independent of creation of pneumoperitoneum and changes in position. Acute intraoperative increases in MAP were noted during insufflation of carbon dioxide and reverse Trendelenburg positioning (P < 0.05). A four-fold increase in plasma concentrations of renin and aldosterone was noted after pneumoperitoneum and reverse Trendelenburg positioning (P > 0.05). There was a linear correlation between changes in plasma renin and aldosterone concentrations and MAP (r = 0.97 and r = 0.85, respectively). Prolactin concentrations increased four-fold after induction of anaesthesia. Cortisol, HGH, adrenaline and noradrenaline concentrations increased after deflation of the pneumoperitoneum. The time profile-concentration changes of increased MAP and renin-aldosterone suggests a cause-effect relationship. Increased intra-abdominal pressure and reverse Trendelenburg positioning may reduce cardiac output and renal blood flow. The early increase in prolactin concentration was probably secondary to the effect of the opioid fentanyl.

Interpretation of random urinary catecholamines and their metabolites in neuroblastoma

This study reports experience in the estimation of urinary catecholamines (uCATs) and their metabolites in the diagnosis and follow-up of neuroblastoma. Random urine samples were assayed for dopamine, noradrenaline and adrenaline, together with their metabolites 4-hydroxy 3-methoxymandelic acid (HMMA) and homovanillic acid (HVA), using HPLC with electrochemical detection. Twenty of 21 patients had elevation of one or more uCATs metabolites at diagnosis. Patients were monitored serially from diagnosis and, in those patients who had delayed resection of primary tumour (n = 13), particular attention was paid to levels at the pre-surgical evaluation as an indicator of persistence of viable disease at the time of surgery; dopamine proved to be the most accurate indicator of persistent disease at this time. Five of these patients developed recurrent disease, 4 of whom had elevation of two or more uCATs metabolites at the time of relapse. Several conclusions can be drawn from this study: (a) results for HMMA, HVA and dopamine in random urine samples will detect all but the most biochemically immature or inert tumours; (b) dopamine may be the most reliable indicator of persistent disease and (c) noradrenaline and adrenaline measurements were of little benefit. As results are expressed in relation to urinary creatinine, excretion of which may be affected by dietary protein and is therefore not constant, borderline results should be repeated.

Oxygen free radicals and acute pancreatitis: fact or fiction?

The effect of oxygen free radical suppression was studied in the taurocholate model of acute pancreatitis in the rat using systemic allopurinol, superoxide dismutase (S.O.D.) and catalase. None of the treatments were beneficial which suggests that oxygen free radical suppression is unlikely to be clinically beneficial in acute pancreatitis.

Pharmacological manipulation of acute cyclosporin ischemic renal injury with trimetazidine

Cyclosporin has had a major impact on organ transplantation, but associated nephrotoxicity is a significant problem. Renal hypothermia, a known anti-ischemic maneuver, limits cyclosporin-ischemic renal failure. Pharmacological manipulation with an anti-ischemic agent, such as trimetazidine, may prevent cyclosporin nephrotoxicity. We tested this hypothesis in a canine single kidney model of cyclosporin-enhanced ischemic renal failure. Trimetazidine treatment was associated with significantly better biochemical and histological markers of renal function and structure. Trimetazidine may have a role to play in protecting against cyclosporin nephrotoxicity in clinical renal transplantation.

A canine model of cyclosporine enhanced ischemic renal injury

Clinical reports of increased graft primary non function in patients receiving cyclosporine in whom the anastomosis time is prolonged (greater than 30 minutes) suggest a synergism between the nephrotoxic effects of cyclosporine and the ischaemia occurring during transplantation. Using unilaterally nephrectomised greyhound dogs, sixty minutes ischaemia and cyclosporine 10 mg./kg./day we have produced an animal model of cyclosporine enhanced ischaemia renal failure. Structural and functional data suggests the proximal tubule is the main site of injury.

Prevention of cyclosporine enhanced ischaemic renal injury using induced hypothermia

Cyclosporine is associated with an increased incidence of graft primary non function and poorer long term graft function in patients with prolonged ischaemia times. We evaluated the role of hypothermia in preventing this synergism between the nephrotoxic effects of cyclosporine and ischaemia in a canine model. Induced renal hypothermia prevented this synergism.

Early detection of acute myocardial infarction: additional diagnostic information from serum concentrations of myoglobin in patients without ST elevation

The value of the 12 lead electrocardiogram, serum total creatine kinase, creatine kinase MB isoenzyme, and myoglobin for the early detection of infarction was evaluated within one hour of admission to the coronary care unit in 82 consecutive patients with suspected myocardial infarction. The 51 patients in whom infarction was diagnosed during the first 24 hours after admission had a higher prevalence of ST elevation (64% v 11%), higher median serum myoglobin (136 micrograms/l v 34 micrograms/l), higher serum creatine kinase (77 IU/l v 34 IU/l), and higher MB isoenzyme (7 IU/l v 4 IU/l) than those in whom it was not. Stepwise logistic regression analysis in 70 patients in whom the electrocardiogram and serum myoglobin were suitable for analysis showed that serum myoglobin was the variable most closely associated with infarction, and contributed additional diagnostic information when ST elevation was entered into the model first. Serum myoglobin remained associated with myocardial infarction when patients who had had symptoms for less than six hours were analysed. An algorithm based on a rapid agglutination test for myoglobin and ST elevation on the electrocardiogram gave an accurate diagnosis in 82% of patients. This approach gave early and rapid recognition of acute myocardial infarction and warrants further examination.

Heart rate and metabolic response to competitive squash in veteran players: identification of risk factors for sudden cardiac death

We studied 10 older males during a competitive game and the early post-exercise period to define the metabolic response to squash in veteran players. For comparison, all subjects were also studied during exhaustive treadmill exercise. Squash caused a dramatic increase in heart rate (150%), and circulating levels of noradrenaline (164%), adrenaline (93%), lactate (202%) and free fatty acids (67%). These effects were independent of haemoconcentration. The early post-exercise period (5 min) was characterized by persistent elevation of plasma catecholamines, lactate, and free fatty acids, hypokalaemia and ventricular arrhythmias. The heart rate and metabolic responses to squash were similar in pattern and magnitude to those observed during treadmill exercise, highlighting the strenuous nature of squash as a recreation sport. While these changes may represent appropriate physiological adaptation to exercise in health, each has been implicated in the pathogenesis of fatal ventricular arrhythmias in subjects with ischaemic heart disease. These data support the contention that squash may be an inappropriate form of exercise for older men with coronary artery disease.

Hypophosphatemia complicating bronchodilator therapy for acute severe asthma

Hypophosphatemia has been recently highlighted as a reversible cause of respiratory muscle hypocontractility and reduced tissue oxygen extraction in patients with chronic obstructive lung disease and asthma. To define the prevalence and mechanism of hypophosphatemia under these circumstances, we studied phosphate homeostasis in 22 patients with chronic asthma, who had been hospitalized for emergency bronchodilator therapy. Serum phosphate concentration was normal in all patients on presentation, and fell after the initiation of bronchodilator therapy. Twelve patients (54%) developed hypophosphatemia (serum phosphate, less than 0.8 mmol/L). Urinary phosphate level fell in parallel. A negative correlation was observed between serum phosphate and serum theophylline concentrations, and a positive correlation between serum and urinary phosphate concentrations. No correlation was found between serum phosphate and serum albumin or urea concentration. These data indicate that hypophosphatemia is a common metabolic abnormality during the emergency treatment of asthma. The underlying mechanism appears to be drug-induced phosphate flux from the extra-cellular to the intracellular space. We suggest that the serum phosphate level be monitored in patients undergoing emergency treatment of bronchospasm, particularly if a prolonged period of bronchodilator therapy is required or if respiratory muscle fatigue supervenes.

Effect of beta-blockers on exercise double product (systolic blood pressure x heart rate)

1 The effect of single oral doses of six beta-receptor antagonists on exercise-induced changes in double product (systolic blood pressure x heart rate) were studied in 25 human volunteers. 2 Three doses of propranolol, nadolol, oxprenolol, pindolol, timolol and atenolol were selected for study on the basis of in vivo beta-blocking potency. 3 Although all beta-blockers studied reduced the double product response to exercise, the pharmacodynamics of this effect differed markedly. 4 Pharmacodynamic half-lives, estimated for the drug tested, were 39 h for nadolol, atenolol 21 h, timolol 15 h, oxprenolol 13 h, propranolol 11 and pindolol 8 h. 5 These results suggest that the clinical choice of a beta-blocker with the least problems of compliance can be made on the basis of pharmacodynamics as well as pharmacological profile.