Potassium hydrogen oxalate

Direct observations: clinical cases, poisoning incidents and other

Administrative data

Endpoint:

direct observations: clinical cases, poisoning incidents and other

Type of information:

experimental study

Adequacy of study:

other information

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study is not performed according to a recognized test guideline and there is no information about GLP compliance. The study makes use of observations of subjects fallen to poisoning.

Data source

Reference

Reference Type:

publication

Title:

Plasma oxalic acid and calcium levels in oxalate poisoning

Author:

Zarembski, P.B., Hodgekinson, A.

Year:

1967

Bibliographic source:

Journal of Clinical Pathology, Vol 20, nr 3, pp 283 - 285

Materials and methods

Study type:

poisoning incident

Endpoint addressed:

not applicable

Test guideline

Qualifier:

no guideline required

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Potassium hydrogen oxalate

EC Number:

204-873-0

EC Name:

Potassium hydrogen oxalate

Cas Number:

127-95-7

Molecular formula:

C2H2O4.K

IUPAC Name:

potassium hydrogen oxalate

Constituent 2

Reference substance name:

Ethane-1,2-diol

EC Number:

203-473-3

EC Name:

Ethane-1,2-diol

Cas Number:

107-21-1

IUPAC Name:

ethylene glycol

Details on test material:

- Name of test material (as cited in study report): potassium hydrogen oxalate; ethylene glycol

Method

Subjects:

- Number of subjects exposed: 5
- Sex: 4 female, 1 male
- Age:
MRF (F) 43
EAL (F) 63
MB (F) 20
PEB (F) 49
JG (M) 57
- Race: no data
- Demographic information: no data
- Known diseases: no data
- Other: no data

Route of exposure:

oral

Reason of exposure:

other: intentional suicide

Exposure assessment:

estimated

Results and discussion

Clinical signs:

Elevation of the plasma oxalic acid level results in an increase in the calcium x oxalate ion product. Since calcium oxalate is only sparingly soluble in aqueous solutions at physiological pH it would be expected to precipitate in the tissues. Such a process might account for the greatly reduced plasma total calcium levels which were observed (Table II). However, no crystals were seen in sections of intestine, liver, or brain from the present patients.

Any other information on results incl. tables

			PLASMA AND TISSUE OXALIC ACID LEVELS
			Oxalic Acid (1)
Patient	Sex	Age	Blood	Stomach Contents	Intestine	Liver	Brain
M.R.F.	F	43	2	40
E.A.L.	F	63	7,72	167	-
M.B.	F	20	10,95	225	72	382	2,14
P.E.B.	F	49	0,37	-	-	-	-
J.G.	M	57				24,5	-
Controls			0.06-0.30	0-5	0,5	0,3	0,1
Normal range			0.10-0.28	0-5	0,5	0,3	0,1
(1) Expressed as mg. anhydrous oxalic acid per 100 ml. or per 100 g. wet tissue.

Table 2	PLASMA CALCIUM LEVELS
	Plasma Calcium (mg. %)
Patient	Total	Ultrafilterable
E.A.L.	4,1	-
M.B.	3,7	1,9
P.E.B.	9,8	-
Controls	10.6-15.0	6.4-12.9
Normal range	9.3-10.7	5,7- 6,8

Applicant's summary and conclusion

Conclusions:

It is of interest that the level of total calcium in the `control' post-mortem plasma samples was higher than normal (Table II). This effect might be due to withdrawal of calcium from the skeleton. Alternatively, it might be due to an efflux of intracellular calcium into the extracellular fluids.

Executive summary:

Observations are reported on five cases of suicide or attempted suicide by poisoning with oxalic acid or ethylene glycol. Elevated oxalic acid levels were observed in the plasma, stomach contents, and a number of tissues. Raised oxalic acid levels in plasma were associated with reduced total and ultrafilterable calcium levels. It is suggested that the reduction in plasma total calcium level is due mainly to the deposition of calcium oxalate in the soft tissues, but inhibition of the parathyroid glands may be a contributory factor. Microscopic examination of various tissues indicated that oxalic acid is deposited in the tissues in two forms: (1) crystalline calcium oxalate dihydrate in the kidney and (2) a non-crystalline complex of calcium oxalate and lipid in liver and other tissues.