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Ciguatera poisoning
14
ABSTRACTS
THE ESTIMATION OF OXYGEN AVAllABlLlTY IN ARTERIAL BLOOD AND THE DERIVATION OF ITS REFERENCE RANGE FROM VENOUS ELOOD. D. Kanowski. A. Clague. Division of Chemical Pathology, Royal Brisbane Hospital, Herston, Q.4029. We have developed a new parameter to describe the amount of oxysen in arterial blood which is available for release at tissue level. We have called it "Maximum Available Oxygen'. It is calculated using a model of the oxygen dissociation curve described by Siggaard-Andersen and associates. The traditional parameters which describe the capacity of arterial blood to transport oxygen are oxygen tension @02) and haemoglobin oxygen saturation (502). These parameters, even in combination, may give misleading information about the ability of the patient's arterial blood to deliver oxygen to the tissues. A further problem for arterial blood gas analysis has been the difficulty in establishing accurate reference ranges, as normal individuals are infrequently tested.
CAN PROSTATE SPECIFIC ANTIGEN PREDICT BONE METASTASES? A. Miller, M. Lichtenstein, S . Ratnaike.' Departments of Biochemistry and Nuclear Medicine, Royal Melbourne Hospital, Parkville, Victoria. 3050
The aim of our study was to determine whether a normal or raised Prostate Specific Antigen (PSA) level could negate the need for a bone scan in the staging or post-therapeutic follow-up of carcinoma of the prostate. A retrospective study was made of 759 consecutive patients who had had PSA levels assayed in our laboratory. We selected the 147 patients in whom a bone scan investigation was performed within one month of the PSA level determination. Patients were grouped according to PSA concentrations and the likelihood of metastatic disease on bone scan. Results as shown: PSA
old0 0-4 4 -10
10 -50
>50 Total
n
53 17 28
49
I47
Bone Scan Report Intermediate or Normal or significant ("A) insignificant (%) 43 17 15 7 82
( 81)
(100) ( 53) ( 14) ( 56)
10
0
13
42 65
(19) ( 0)
(47) (86) (44)
Our new parameter describes the amount of oxygen which is released from the arterial blood specimen when its p 0 2 falls to a value of 30 mmHg (4.0 kPa). We believe that this single term provides an integrated assessment of all the relevant variables which influence the oxygen status of blood. It is also a simpler concept than other new parameters recently described in the literature.
PSA levels are dependent on androgens1. When exclusions were made for patients being followed-up after anti-testosterone intervention, 7 patients (I 4%) with a normal PSA level and prostatic carcinoma had an intermediate or significant bone scan report. Prostatic acid phosphatase was found to be of no additional value to PSA in predicting hone scan findings. Our results show that while PSA levels tend to correlate with bone scan fmdings, it cannot be used with certainty to predict bone scan findings and hence abrogate the need for a bone scan.
We have determined reference ranges for Maximum Available Oxygen. This was done using a calculation based on the above model applied to data from normal venous blood.
lBilhartz DL, Young CYF, Flanagan WF, He W, Tindall DJ. Androgen regulation of prostate specific antigen (PSA) in human prostate carcinoma. J Urol 1990; 143: 203A (Abstract)
Presenter.
Dr David Kanowski. Division of Chemical Pathology. Royal Brisbane Hospital, Herston, Q. 4029.
ASSESSMENT OF CHEiMICAL PATHOLOGY SCREENING IN FEMORAL NECK FRACTURE ADMISSIONS. *Sikaris K.A. Read A.. Baker C..#Osborne L. & Janus E.D. Departments o f Chemical Pathology & #Quality Assurance, St Vincents Hospital, Victoria Parade, Fitzroy, Victoria 3063. Clinical costing requires clinicians and pathologists to rationalise investigation o f specific diseases. We evaluated the Chemical Pathology results o f 51 admissions f o r a femoral neck fracture collected over 12 months. The rate o f abnormality o f a test result has been shown, by many other groups, to be directly related to the rate o f clinical significance o f the test. The median age was 79 years and 65% were female. Admissions were for a n average o f 13 days and there was a n average o f 6.6 specimens for each admission. All 51 patients h a d electrolytes requested on admission and 68% showed a n abnormality. Elevations o f plasma urea, creatinine a n d potassium, a n d lowered plasma sodium, were the most common abnormalities. Almost h a l f h a d liver function tests (LFTs) ordered, and one third o f these contained a n abnormality, usually a n isolated elevation in Alkaline Phosphatase (ALP). Testing performed later during the admission showed a higher rate o f electrolyte abnormalities (80%) and some further LFTs w i t h a n elevated ALP. Specific testing f o r metabolic bone disease and malignancy (eg myeloma) was rarely performed. On the basis o f these results it was suggested that admissions f o r femoral neck fractures continue to be screened for electrolyte and ALP abnormalities. The departments o f Anaesthesia and Orthopaedics, together with Pathology departments w i l l develop a routine protocol for the investigation o f patients with femoral neck fractures and further assess the need to screen for markers of pathological fractures.
CIGUATERA POISONING
M. F. Capra. Centro for Biological Population Management, Queensland University of Technology, GPO Box 2434,Brisbane, OLD. 4001. Human ciguatera poisoning has a circumtropical distribution and a close association with coral reef fish. Cases of poisoning have been reported along the tropical coast 01 Queensland and in the Northern Territory. The largest single outbreak of ciguatera poisoning, in Australia, occurred in Sydney in 1987. Human intoxication follows consumption of a variety of tropical fish which contain a potent toxin, ciguatoxin. in their tissues. Ciguatoxin is believed to be elaborated by a benthic dinoflagellate Garnbierdiscusfoxicus and passed through the food chain to higher level carnivores such as Coral Trout. Human victims of ciguatoxin usually present with gastrointestinal symptoms within six to twelve hours of ingestion of fish. Following the onset of gastrointesllnal disturbances a variety of neurological symptoms are manifested. The duration and type of symptoms displayed by the Sydney victims of ciguatera poisoning will be presented. Ciguatoxin is believed to exert a fundamental physiological action on the voltage dependent sodium channels in nerve fibres. Electrophysiological studies perlormed on rat and human nerves indicate that ciguatoxin.slows conduction velocity and prolongs the absolute and relative relractory periods. The duration and magnitude of the supernormal period is also increased. Identical changes in these nerve conduction parameters have also been recorded from fish nerves. Fish nerves. in vivo, may be protected from ciguatoxin by inherent partitioning mechanisms. Until recently there was no effective therapy lor the ciguatera syndrome, Intravenous infusion of mannitol has been reported to effectively alleviate symptoms by a number of workers, however the physiological mechanisms underlying this treatment are as yet not elucidated.
ABSTRACTS
THE ESTIMATION OF OXYGEN AVAllABlLlTY IN ARTERIAL BLOOD AND THE DERIVATION OF ITS REFERENCE RANGE FROM VENOUS ELOOD. D. Kanowski. A. Clague. Division of Chemical Pathology, Royal Brisbane Hospital, Herston, Q.4029. We have developed a new parameter to describe the amount of oxysen in arterial blood which is available for release at tissue level. We have called it "Maximum Available Oxygen'. It is calculated using a model of the oxygen dissociation curve described by Siggaard-Andersen and associates. The traditional parameters which describe the capacity of arterial blood to transport oxygen are oxygen tension @02) and haemoglobin oxygen saturation (502). These parameters, even in combination, may give misleading information about the ability of the patient's arterial blood to deliver oxygen to the tissues. A further problem for arterial blood gas analysis has been the difficulty in establishing accurate reference ranges, as normal individuals are infrequently tested.
CAN PROSTATE SPECIFIC ANTIGEN PREDICT BONE METASTASES? A. Miller, M. Lichtenstein, S . Ratnaike.' Departments of Biochemistry and Nuclear Medicine, Royal Melbourne Hospital, Parkville, Victoria. 3050
The aim of our study was to determine whether a normal or raised Prostate Specific Antigen (PSA) level could negate the need for a bone scan in the staging or post-therapeutic follow-up of carcinoma of the prostate. A retrospective study was made of 759 consecutive patients who had had PSA levels assayed in our laboratory. We selected the 147 patients in whom a bone scan investigation was performed within one month of the PSA level determination. Patients were grouped according to PSA concentrations and the likelihood of metastatic disease on bone scan. Results as shown: PSA
old0 0-4 4 -10
10 -50
>50 Total
n
53 17 28
49
I47
Bone Scan Report Intermediate or Normal or significant ("A) insignificant (%) 43 17 15 7 82
( 81)
(100) ( 53) ( 14) ( 56)
10
0
13
42 65
(19) ( 0)
(47) (86) (44)
Our new parameter describes the amount of oxygen which is released from the arterial blood specimen when its p 0 2 falls to a value of 30 mmHg (4.0 kPa). We believe that this single term provides an integrated assessment of all the relevant variables which influence the oxygen status of blood. It is also a simpler concept than other new parameters recently described in the literature.
PSA levels are dependent on androgens1. When exclusions were made for patients being followed-up after anti-testosterone intervention, 7 patients (I 4%) with a normal PSA level and prostatic carcinoma had an intermediate or significant bone scan report. Prostatic acid phosphatase was found to be of no additional value to PSA in predicting hone scan findings. Our results show that while PSA levels tend to correlate with bone scan fmdings, it cannot be used with certainty to predict bone scan findings and hence abrogate the need for a bone scan.
We have determined reference ranges for Maximum Available Oxygen. This was done using a calculation based on the above model applied to data from normal venous blood.
lBilhartz DL, Young CYF, Flanagan WF, He W, Tindall DJ. Androgen regulation of prostate specific antigen (PSA) in human prostate carcinoma. J Urol 1990; 143: 203A (Abstract)
Presenter.
Dr David Kanowski. Division of Chemical Pathology. Royal Brisbane Hospital, Herston, Q. 4029.
ASSESSMENT OF CHEiMICAL PATHOLOGY SCREENING IN FEMORAL NECK FRACTURE ADMISSIONS. *Sikaris K.A. Read A.. Baker C..#Osborne L. & Janus E.D. Departments o f Chemical Pathology & #Quality Assurance, St Vincents Hospital, Victoria Parade, Fitzroy, Victoria 3063. Clinical costing requires clinicians and pathologists to rationalise investigation o f specific diseases. We evaluated the Chemical Pathology results o f 51 admissions f o r a femoral neck fracture collected over 12 months. The rate o f abnormality o f a test result has been shown, by many other groups, to be directly related to the rate o f clinical significance o f the test. The median age was 79 years and 65% were female. Admissions were for a n average o f 13 days and there was a n average o f 6.6 specimens for each admission. All 51 patients h a d electrolytes requested on admission and 68% showed a n abnormality. Elevations o f plasma urea, creatinine a n d potassium, a n d lowered plasma sodium, were the most common abnormalities. Almost h a l f h a d liver function tests (LFTs) ordered, and one third o f these contained a n abnormality, usually a n isolated elevation in Alkaline Phosphatase (ALP). Testing performed later during the admission showed a higher rate o f electrolyte abnormalities (80%) and some further LFTs w i t h a n elevated ALP. Specific testing f o r metabolic bone disease and malignancy (eg myeloma) was rarely performed. On the basis o f these results it was suggested that admissions f o r femoral neck fractures continue to be screened for electrolyte and ALP abnormalities. The departments o f Anaesthesia and Orthopaedics, together with Pathology departments w i l l develop a routine protocol for the investigation o f patients with femoral neck fractures and further assess the need to screen for markers of pathological fractures.
CIGUATERA POISONING
M. F. Capra. Centro for Biological Population Management, Queensland University of Technology, GPO Box 2434,Brisbane, OLD. 4001. Human ciguatera poisoning has a circumtropical distribution and a close association with coral reef fish. Cases of poisoning have been reported along the tropical coast 01 Queensland and in the Northern Territory. The largest single outbreak of ciguatera poisoning, in Australia, occurred in Sydney in 1987. Human intoxication follows consumption of a variety of tropical fish which contain a potent toxin, ciguatoxin. in their tissues. Ciguatoxin is believed to be elaborated by a benthic dinoflagellate Garnbierdiscusfoxicus and passed through the food chain to higher level carnivores such as Coral Trout. Human victims of ciguatoxin usually present with gastrointestinal symptoms within six to twelve hours of ingestion of fish. Following the onset of gastrointesllnal disturbances a variety of neurological symptoms are manifested. The duration and type of symptoms displayed by the Sydney victims of ciguatera poisoning will be presented. Ciguatoxin is believed to exert a fundamental physiological action on the voltage dependent sodium channels in nerve fibres. Electrophysiological studies perlormed on rat and human nerves indicate that ciguatoxin.slows conduction velocity and prolongs the absolute and relative relractory periods. The duration and magnitude of the supernormal period is also increased. Identical changes in these nerve conduction parameters have also been recorded from fish nerves. Fish nerves. in vivo, may be protected from ciguatoxin by inherent partitioning mechanisms. Until recently there was no effective therapy lor the ciguatera syndrome, Intravenous infusion of mannitol has been reported to effectively alleviate symptoms by a number of workers, however the physiological mechanisms underlying this treatment are as yet not elucidated.