48 in what would seem to have been the last year of irreversible natural ageing. Should this make us think again about paragraph 23 of the memorandum on Services for Mental Illness Related to Old Age (1971)? Should not most of these patients die in accommodation designated as geriatric rather than psychiatric?

diorespiratory failure,

Stone House

Hospital,

Dartford,

J. P. CRAWFORD

Kent

NORMALISATION AND SI UNITS

SIR,—Lennox1 has suggested a solution to difficulties over SI units. I may have misunderstood his letter, but his suggestion is not new. Hofmannin addition to describing a now well-known method for determining "normal" limits from cumulative patient data also described a "normal quotient scale",3 based on the standard deviation of a normal population. In his scheme standard deviation (s.D.) equivalents are transformed to a positive number scale in which mean normal is 100 and the 2s.D. range is 90-110. Many clinicians are frightened by statistics, and Lennox will do nothing to gain their confidence by recommending dry works such as "Bradford Hill".4 (Perhaps newer generations will be less averse to statistics having been taught their value and limitations from an

earlier

age.) s.D. units are derived very simply: = S.D. unit unit=

X-M,

S.D.

where X = value obtained, M mean of normal population, and s.D. = standard deviation of normal population. S.D. units can easily be reported graphically, and for diehards absolute values can still be reported alongside. We had considered changing to this system of reporting and had had some painless internal practice when it appeared that SI units would be more generally supported. A number of critical letters have appeared in The Lancet and elsewhere suggesting that the change to SI is full of difficulties, and I have drawn attention to possible dangers of uncritical acceptance of these units/ Nevertheless many hospitals have successfully negotiated the transition to SI: perhaps the present controversy is due to their not stating how easy this change has been. Others also have suggested "normalisation" for laboratory reporting’6 but if this is a simple solution to the unit problem what a pity that it was not examined before SI units were introduced on a national basis. "Normalisation" should be thoroughly examined---even now it is not too late since many are still struggling to learn the SI units of clinical value, or, like our transatlantic colleagues, have refused to change. Let us have published the figures of how many areas have changed to SI, and whether doctors are in favour of the change or not. Would doctors favour a change to normalisation or, as I suspect, would they prefer no change at all? There must be somebody with sufficient time to do such a simple monitoring project, even at the risk of being awarded a PH.D for doing so. =

States of Jersey The Parade,

Pathological Laboratory,

Jersey, Channel Islands.

J. J. TAYLOR

BREAST EXAMINATION IN OBESE PATIENTS

SIR--Examination of the axillae of obese patients with disease may be difficult, particularly for the group of

Dreast

lymph-nodes situated in the pad of adipose tissue between the pectoralis major and minor muscles. The probing fingers may push the pad into the wedge-shaped space between the muscles, and the enclosed nodes become impalpable. 1. 2. 3. 4. 5. 6. 7.

Lennox, B. Lancet, 1975, ii, 1085. Hofmann, R. G. J. Am. med. Ass. 1963, 185, 150. Hofmann, R. G. GP, 1964, 30, 112. Hill, A. B. Principles of Medical Statistics, London, 1971. Taylor, J. J. Br. med. J. 1975, iii, 226. Rushmen, R. F. J. Am. med. Ass. 1968, 206, 836. Schoen, I., Brooks, S. H. Am. J. clin. Path. 1970, 53, 190.

I have found an additional step in routine examination to be useful in detecting these nodes. The patient is asked to lie supine with the arms resting in the adducted position. To examine the right axilla the examiner stands on the patient’s right side and depresses with his right hand the pectoralis major muscle downwards towards the chest wall; this manoeuvre causes the pad of adipose tissue between the muscles to prolapse towards the lateral border of the pectoralis major muscle, where enclosed nodes are readily palpated by the left hand. The left axilla is examined with the left hand depressing the muscle and the right hand palpating. I have found this method more reliable in the detection of this group of nodes in obese patients than the usual method. Kingston General Hospital, Kingston on Thames, Surrey.

N. G. BUCHAN

DIMINISHED T.S.H. SECRETION DURING ACUTE NON-THYROIDAL ILLNESS IN UNTREATED PRIMARY HYPOTHYROIDISM

SIR--Dr McLarty and his colleagues (Aug. 9, p. 275) found changes in thyroid function in clinically euthyroid patients after acute stress. After myocardial infarction and cerebrovascular accidents there is a significant fall of both total serum T3 and T4, the fall in T3 being greater than the fall in T4. These changes do not appear to be due to changes in thyroid-hormone binding proteins, since free T4 and T3 indices parallel the total T4 and T3 changes. The changes observed in these "sick euthyroid" patients may be due to one or more of the folTHYROID FUNCTION IN DIABETIC HYPOTHYROID PATIENT IN PRECOMA AND

DURING RECOVERY

mechanisms: hypothalamic-pituitary dysfunction, decreased peripheral conversion of T4 to T3, and/or the production of reverse T3.’ I have made sequential measurements in one patient which demonstrate hypothalamic-pituitary dysfunction during acute

lowing

non-thyroidal illness in untreated primary hypothyroidism. The patient, a 39-year-old diabetic, was admitted in precoma due to ketoacidosis (blood-glucose 95 nmoV1, ketonuria, pH 7-11) associated with a respiratory-tract infection. She had had a thyroidectomy for thyrotoxicosis 7 years before. Histologically, there was evidence of lymphocytic infiltration, and thyroid autoantibodies were present in high titres. There were no overt clinical features of thyroid dysfunction on admission. She was treated with a low-dose intramuscular insulin regimen, saline infusion, potassium supplements, and ampicillin. Stabilisation was difficult, but satisfactory control was achieved after 10 days. Serial measurements of thyroid-hormone and thyroid-stimulating-hormone (T.S.H.) levels during the acute phase of her illness and her convalescence are shown in the table. On the morning after her admission total serum-T4 levels were low and total serum-T3 and T.S.H. levels were undetectable. 2-3 weeks later, before discharge, total serum-T4 levels had risen to just below the normal range, total serum-T3 levels were within the normal range, and T.S.H. levels were raised. 3 months after admission, subclinical primary hypothyroidism was confirmed by a persistently low serum-T4, a total serum-T3 at the upper end of the 1.

Wenzel,

K.

M., Meinhold, H. Lancet, 1975, ii, 413.

Letter: Normalisation and SI units.

48 in what would seem to have been the last year of irreversible natural ageing. Should this make us think again about paragraph 23 of the memorandum...
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