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Serum levels of thyroid-stimulating hormone in hyperlipoproteinemia
293
Clinica Chimica Acta, 62 (1975) 293-297 @ Elsevier Scientific Publishing Company,
Amsterdam
- Printed
in The Netherlands
CCA 7151
SERUM LEVELS OF THYROID-STIMULATING HYPERLIPOPROTEINEMIA
HORMONE
IN
B. VESSBY and L. WIDE Department Akademiska
(Received
of Geriatrics, University of Uppsala and the Department sjukhuset, Uppsala (Sweden)
of Clinical
Chemistry,
March 11, 197 5)
Summary Similar serum lipoprotein abnormalities have been demonstrated in hyperlipoproteinemia type III and hypothyroidism. ln this study the levels of thyroid-stimulating hormone in serum were determined in clinically euthyroid patients with different types of hyperlipoproteinemias and in subjects with a normal lipoprotein pattern. The mean value for thyroid-stimulating hormone was significantly higher in the group with hyperlipoproteinemia type III than in normal controls (p < 0.01) and in the group with hyperlipoproteinemia type II A (p < 0.02). The levels of thyroid-stimulating hormone were positively correlated to the triglyceride and cholesterol concentration in the very low density lipoprotein fraction and the “III-index”. Introduction Hyperlipoproteinemia type III or “broad beta disease” is characterized by an accumulation of “intermediary lipoprotein” particles with composition and density characteristics intermediate between very low density lipoproteins (VLDL, d < 1.006) and low density lipoproteins (LDL, d 1.006-1.063) [l] . The ratio cholesterol/triglycerides in VLDL is increased [l] and LDL triglyceride levels are elevated [2] . Strikingly similar lipoprotein abnormalities have been recorded in hypothyroidism: a cholesterol enriched VLDL fraction and hypertriglyceridemia attributed to high LDL triglyceride levels [3] . An unusual VLDL apoprotein composition has also been reported in type III and hypothyroidism with a common increase of a certain peptide, designated the arginine-rich peptide, relative to the normally predominating apoprotein peptides [ 41. Both hypothyroidism and the genetically determined “broad beta disease” seem to result in a similar lipoprotein abnormality. In hypothyroidism, in contrast to type III, this is often accompanied by an accumulation of LDL particles of ordinary composition (d 1.019-1.063) causing increased LDL cholesterol levels.
294
Increased levels of thyroid-stimulating hormone (TSH) ated with primary hypothyroidisrl. The present study was lyze the levels of TSH in different hyperlipoproteinemias in a possible coexistence of a subclinical hypothyroidism and malities.
in serum is associundertaken to anaorder to investigate lipoprotein abnor-
Materials and methods As a part of a continuing health screening of 50-year-old men in Uppsala, Sweden, lipoprotein analyses were performed and classification of the lipoprotein pattern was done according to Fredrickson et al. [l] using the criteria suggested by Beaumont et al. [ 51. The cutting points for “normality” were 1.5 mmol/l for VLDL triglycerides and 190 mg/lOO ml for LDL cholesterol. Serum lipoproteins were separated into VLDL, LDL and high density lipoproteins (HDL, d > 1.063) by consecutive spins in a Beckman L 2 65 B ultracentrifuge [6]. Agarose electrophoresis on whole serum and top and bottom fractions at d = 1.006 was performed within 36 hours after isolation [7]. Cholesterol and triglyceride determinations were done in a Technicon Auto Analyzer type II [8]. No~olipidemic 50-year-old men (n = 23) were randomly sampled for analysis of TSH levels in serum and compared to patients with hyperlipoproteinemia type Ii A (n = 19), III (n = 14) and IV (n = 2.2) from the same population. All subjects were clinically euthyroid. A summary of the lipoprotein levels in the different groups of patients is shown in Table I. Sera exhibiting a “slow pre-beta” band in VLDL on agarose electrophoresis [Z] were not included in the study. The TSH concentration in serum was assayed by the radio-immunosorbent technique [ 91 using the recently described modification where antibodies were indirectly coupled to the solid phase [lo). The antibodies were human-antibovine-TSH coupled to bovine TSH on CNBr-activated ultrafine Sephadex particles. The TSH preparation, used for labelling with ’ ’ ’ I, was purified according to Roos et al. [ll] and had an activity of 12 U/mg. The sera were assayed in 0.1 ml aliquots in duplicate with incubation for 24 hours at room tempera-
TABLE
I
LIPOPROTEIN AND
LIPID
LEVELS
HYPERLIPOPROTEINEMIA
IN
50-YEAR-OLD (MEAN
MEN
WITH
NORMAL
LIPOPROTEIN
VLDL
“III-index”
LDL
TG
Chol
ChoI/TG
TG
Chol
(mmoIi1)
(mu
(m!z/
(mmoI/l)
tmgi
100
ml)
100
ml)/
100
Chol/TG (mu ml)
100
Normals
01 = 23)
0.85
+ 0.07
17
+
2
20.9
* 1.1
0.46
?: 0.02
149
*
II A
(n = 19)
1.12
+ 0.04
23 *
2
20.6
1: 1.3
0.65
f 0.03
234
t 14
III
(n = 14)
2.71
+ 0.61
96
18
37.1
* 1.7
0.82
i 0.08
169+
16
IV
(n = 22)
2.27
t 0.14
4Oi
0.8
0.55
i 0.03
149+
4
3
17.SIt
ml)/
(mmolf)
(mmoI/l)
i
PATTERNS
f S.E.)
5
330+ 364 210+ 281
13
0.64
+ 13
0.59
f 0.05
13
1.85
t 0.13
i: 11
0.67
i 0.05
f 0.03
295
ture. The sensitivity was 0.5 pU/ml of serum. The standard preparation was TSH MRC 68/38. (Division of Biological Standards, National Institute for Medical Research, London). The TSH levels were correlated to different lipoprotein lipid variables including a “III-index*“, an index created in an effort to estimate the amount of “intermediary” particles in plasma without having access to the analytical ultracentrifuge (B. Vessby, to be published). Results The results of the analyses of TSH in different types of hyperlipoproteinemias are shown in Fig. 1. All TSH-values were within what is considered the “normal” range with a small variance for “normals”, type II A and IV. The patients with type III showed a wider range of TSH-values. The mean TSHvalue in the type III group was significantly higher than the TSH-value for
”I
2.61 f 0.U I
5
5
IL5 t 0.32
i
i
n=23
Control
2.58?0.13
3
4
!I A
“=I9
III
!Yl=lL
5
6
TSH PC/ml
Fig. 1. Thyroid-stimulating hormone (TSH) in serum (5 + S.E.) in patients with different hyperlipoproteinemias and in subjects with a normal lipoprotein pattern.
* “fD_~dex”
=
ChoUTG ratio in VLDL X 10 Chol/TG ratio in LDL
.
types of
296
TABLE
II
CORRELATION YEAR-OLD Number
BETWEEN
TSH-LEVELS
AND
LIPOPROTEIN
LIPID
LEVELS
IN
A
GROUP
OF
50-
MEN of observations.
.Y
Y
78.
Correlation
TSH
TG
TSH
Chol
VLDL
TSH
Cbol/TG
TSH
TG
VLDL
TSH
Chol
TSH
Chol/TG
TSH
III-index
* p <
0.02.
* * p <
0.01.
VLDL
LDL LDL
t-value
0.29
2.59*
0.36
3.32**
0.22
1.95
0.17
1.54
0.00 LDL
coefficient
-0.17 0.28
0.00 -1.48 2.51*
“normals” Gr,< 0.01) and in the type II A group (p < 0.02). There were no significant differences between any of the other groups. The TSH levels in the 78 men were positively correlated to the triglyceride and cholesterol levels in VLDL and the “III-index” (Table II). Discussion Care has to be taken in the evaluation of these results. The classification of hyperlipoproteinemia type II A and IV is based on arbitrarily chosen limits for “hyperlipidemia” delineating these types of hyperlipoproteinemias from “normal” lipoprotein patterns [l] . However, the type III diagnosis includes a qualitative aspect, the requirement of a “floating beta band” in VLDL [5]. In this study, only samples showing a typical type III pattern on agarose electrophoresis were included. Although the number of sera analyzed was fairly small, the subjects represented a population homogenous in terms of sex and age. All blood samples were treated similarly and kept deep frozen until analyzed. All TSH analyses were made simultaneously. The findings of significantly higher TSH values in type III than in “normals” and II A is interesting with regard to the similarities in lipoprotein abnormalities recorded in hypothyroidism and “broad beta disease”. Possibly type III and hypothyroidism could share a common etiological factor. It seems more probable, however, that we are dealing with two pathogenetically different disorders interacting with a common metabolic pathway. In a certain number of patients an incompletely expressed type III defect may be unmasked by a subclinical hypothyroidism. Acknowledgement This study was supported Council (Grant 13X-3970).
by a grant from the Swedish
Medical Research
291
References 1
D.S.
2
B.
Fredrickson, Vessby,
R.I.
L.A.
Springer-Verlag, 3
S. RGssner
4
B. Shore,
5 J.L.
Berlin,
and V.
43
H.A.
R.J.
Havel,
7
R.P.
Noble,
8
R.L.
Rush.
9
L. Wide,
R.
10
L. Wide,
S.J.
11
P. Roes,
G. Jacobson
L. Leon
New
York.
G.R.
and
Engl.
in
G. 1974,
20 R.
276 and
(1967) A.
32,
Weizel
94.
(eds),
148,
Res.,
Bragdon,
9 (1968)
Z.
Fejfar,
D.S.
J. Clin.
Invest.,
34
Gemzell
and
Adv.
Autom.
Anal.,
Immunochemistry, and
L. Wide,
P. Roes.
Biochim.
273 III.
356
Biochim.
Biophys. Fredrickson
Res.
Commun..
and
58 (1974)
‘1’. Strasser,
(1955)
1345
693
and J. Turrell,
215,
Atherosclerosis
p. 882
(1974)
Z&s,
Cooper,
J. Med.,
Schettler
891
and J.H.
0.
New
Atherosclerosis,
and J. Porath,
Nillius,
Lees,
Hedstrand,
D. Mason
Carlson,
Eder
J. Lipid AX&I
Salel,
(1970)
6
R.S.
H.
Heidelberg,
A.
L.A.
Organ..
and
and
U. Rosenqvist.
Shore,
Beaumont,
Health
Levy
Carlson
1 (1971)
4 (1967)
503 381
Acta
Endocrinol.,
Suppl.,
174
Biophys.
Acta.
(1975)
247
379
(1973)
1
Bull.
1 World
Clinica Chimica Acta, 62 (1975) 293-297 @ Elsevier Scientific Publishing Company,
Amsterdam
- Printed
in The Netherlands
CCA 7151
SERUM LEVELS OF THYROID-STIMULATING HYPERLIPOPROTEINEMIA
HORMONE
IN
B. VESSBY and L. WIDE Department Akademiska
(Received
of Geriatrics, University of Uppsala and the Department sjukhuset, Uppsala (Sweden)
of Clinical
Chemistry,
March 11, 197 5)
Summary Similar serum lipoprotein abnormalities have been demonstrated in hyperlipoproteinemia type III and hypothyroidism. ln this study the levels of thyroid-stimulating hormone in serum were determined in clinically euthyroid patients with different types of hyperlipoproteinemias and in subjects with a normal lipoprotein pattern. The mean value for thyroid-stimulating hormone was significantly higher in the group with hyperlipoproteinemia type III than in normal controls (p < 0.01) and in the group with hyperlipoproteinemia type II A (p < 0.02). The levels of thyroid-stimulating hormone were positively correlated to the triglyceride and cholesterol concentration in the very low density lipoprotein fraction and the “III-index”. Introduction Hyperlipoproteinemia type III or “broad beta disease” is characterized by an accumulation of “intermediary lipoprotein” particles with composition and density characteristics intermediate between very low density lipoproteins (VLDL, d < 1.006) and low density lipoproteins (LDL, d 1.006-1.063) [l] . The ratio cholesterol/triglycerides in VLDL is increased [l] and LDL triglyceride levels are elevated [2] . Strikingly similar lipoprotein abnormalities have been recorded in hypothyroidism: a cholesterol enriched VLDL fraction and hypertriglyceridemia attributed to high LDL triglyceride levels [3] . An unusual VLDL apoprotein composition has also been reported in type III and hypothyroidism with a common increase of a certain peptide, designated the arginine-rich peptide, relative to the normally predominating apoprotein peptides [ 41. Both hypothyroidism and the genetically determined “broad beta disease” seem to result in a similar lipoprotein abnormality. In hypothyroidism, in contrast to type III, this is often accompanied by an accumulation of LDL particles of ordinary composition (d 1.019-1.063) causing increased LDL cholesterol levels.
294
Increased levels of thyroid-stimulating hormone (TSH) ated with primary hypothyroidisrl. The present study was lyze the levels of TSH in different hyperlipoproteinemias in a possible coexistence of a subclinical hypothyroidism and malities.
in serum is associundertaken to anaorder to investigate lipoprotein abnor-
Materials and methods As a part of a continuing health screening of 50-year-old men in Uppsala, Sweden, lipoprotein analyses were performed and classification of the lipoprotein pattern was done according to Fredrickson et al. [l] using the criteria suggested by Beaumont et al. [ 51. The cutting points for “normality” were 1.5 mmol/l for VLDL triglycerides and 190 mg/lOO ml for LDL cholesterol. Serum lipoproteins were separated into VLDL, LDL and high density lipoproteins (HDL, d > 1.063) by consecutive spins in a Beckman L 2 65 B ultracentrifuge [6]. Agarose electrophoresis on whole serum and top and bottom fractions at d = 1.006 was performed within 36 hours after isolation [7]. Cholesterol and triglyceride determinations were done in a Technicon Auto Analyzer type II [8]. No~olipidemic 50-year-old men (n = 23) were randomly sampled for analysis of TSH levels in serum and compared to patients with hyperlipoproteinemia type Ii A (n = 19), III (n = 14) and IV (n = 2.2) from the same population. All subjects were clinically euthyroid. A summary of the lipoprotein levels in the different groups of patients is shown in Table I. Sera exhibiting a “slow pre-beta” band in VLDL on agarose electrophoresis [Z] were not included in the study. The TSH concentration in serum was assayed by the radio-immunosorbent technique [ 91 using the recently described modification where antibodies were indirectly coupled to the solid phase [lo). The antibodies were human-antibovine-TSH coupled to bovine TSH on CNBr-activated ultrafine Sephadex particles. The TSH preparation, used for labelling with ’ ’ ’ I, was purified according to Roos et al. [ll] and had an activity of 12 U/mg. The sera were assayed in 0.1 ml aliquots in duplicate with incubation for 24 hours at room tempera-
TABLE
I
LIPOPROTEIN AND
LIPID
LEVELS
HYPERLIPOPROTEINEMIA
IN
50-YEAR-OLD (MEAN
MEN
WITH
NORMAL
LIPOPROTEIN
VLDL
“III-index”
LDL
TG
Chol
ChoI/TG
TG
Chol
(mmoIi1)
(mu
(m!z/
(mmoI/l)
tmgi
100
ml)
100
ml)/
100
Chol/TG (mu ml)
100
Normals
01 = 23)
0.85
+ 0.07
17
+
2
20.9
* 1.1
0.46
?: 0.02
149
*
II A
(n = 19)
1.12
+ 0.04
23 *
2
20.6
1: 1.3
0.65
f 0.03
234
t 14
III
(n = 14)
2.71
+ 0.61
96
18
37.1
* 1.7
0.82
i 0.08
169+
16
IV
(n = 22)
2.27
t 0.14
4Oi
0.8
0.55
i 0.03
149+
4
3
17.SIt
ml)/
(mmolf)
(mmoI/l)
i
PATTERNS
f S.E.)
5
330+ 364 210+ 281
13
0.64
+ 13
0.59
f 0.05
13
1.85
t 0.13
i: 11
0.67
i 0.05
f 0.03
295
ture. The sensitivity was 0.5 pU/ml of serum. The standard preparation was TSH MRC 68/38. (Division of Biological Standards, National Institute for Medical Research, London). The TSH levels were correlated to different lipoprotein lipid variables including a “III-index*“, an index created in an effort to estimate the amount of “intermediary” particles in plasma without having access to the analytical ultracentrifuge (B. Vessby, to be published). Results The results of the analyses of TSH in different types of hyperlipoproteinemias are shown in Fig. 1. All TSH-values were within what is considered the “normal” range with a small variance for “normals”, type II A and IV. The patients with type III showed a wider range of TSH-values. The mean TSHvalue in the type III group was significantly higher than the TSH-value for
”I
2.61 f 0.U I
5
5
IL5 t 0.32
i
i
n=23
Control
2.58?0.13
3
4
!I A
“=I9
III
!Yl=lL
5
6
TSH PC/ml
Fig. 1. Thyroid-stimulating hormone (TSH) in serum (5 + S.E.) in patients with different hyperlipoproteinemias and in subjects with a normal lipoprotein pattern.
* “fD_~dex”
=
ChoUTG ratio in VLDL X 10 Chol/TG ratio in LDL
.
types of
296
TABLE
II
CORRELATION YEAR-OLD Number
BETWEEN
TSH-LEVELS
AND
LIPOPROTEIN
LIPID
LEVELS
IN
A
GROUP
OF
50-
MEN of observations.
.Y
Y
78.
Correlation
TSH
TG
TSH
Chol
VLDL
TSH
Cbol/TG
TSH
TG
VLDL
TSH
Chol
TSH
Chol/TG
TSH
III-index
* p <
0.02.
* * p <
0.01.
VLDL
LDL LDL
t-value
0.29
2.59*
0.36
3.32**
0.22
1.95
0.17
1.54
0.00 LDL
coefficient
-0.17 0.28
0.00 -1.48 2.51*
“normals” Gr,< 0.01) and in the type II A group (p < 0.02). There were no significant differences between any of the other groups. The TSH levels in the 78 men were positively correlated to the triglyceride and cholesterol levels in VLDL and the “III-index” (Table II). Discussion Care has to be taken in the evaluation of these results. The classification of hyperlipoproteinemia type II A and IV is based on arbitrarily chosen limits for “hyperlipidemia” delineating these types of hyperlipoproteinemias from “normal” lipoprotein patterns [l] . However, the type III diagnosis includes a qualitative aspect, the requirement of a “floating beta band” in VLDL [5]. In this study, only samples showing a typical type III pattern on agarose electrophoresis were included. Although the number of sera analyzed was fairly small, the subjects represented a population homogenous in terms of sex and age. All blood samples were treated similarly and kept deep frozen until analyzed. All TSH analyses were made simultaneously. The findings of significantly higher TSH values in type III than in “normals” and II A is interesting with regard to the similarities in lipoprotein abnormalities recorded in hypothyroidism and “broad beta disease”. Possibly type III and hypothyroidism could share a common etiological factor. It seems more probable, however, that we are dealing with two pathogenetically different disorders interacting with a common metabolic pathway. In a certain number of patients an incompletely expressed type III defect may be unmasked by a subclinical hypothyroidism. Acknowledgement This study was supported Council (Grant 13X-3970).
by a grant from the Swedish
Medical Research
291
References 1
D.S.
2
B.
Fredrickson, Vessby,
R.I.
L.A.
Springer-Verlag, 3
S. RGssner
4
B. Shore,
5 J.L.
Berlin,
and V.
43
H.A.
R.J.
Havel,
7
R.P.
Noble,
8
R.L.
Rush.
9
L. Wide,
R.
10
L. Wide,
S.J.
11
P. Roes,
G. Jacobson
L. Leon
New
York.
G.R.
and
Engl.
in
G. 1974,
20 R.
276 and
(1967) A.
32,
Weizel
94.
(eds),
148,
Res.,
Bragdon,
9 (1968)
Z.
Fejfar,
D.S.
J. Clin.
Invest.,
34
Gemzell
and
Adv.
Autom.
Anal.,
Immunochemistry, and
L. Wide,
P. Roes.
Biochim.
273 III.
356
Biochim.
Biophys. Fredrickson
Res.
Commun..
and
58 (1974)
‘1’. Strasser,
(1955)
1345
693
and J. Turrell,
215,
Atherosclerosis
p. 882
(1974)
Z&s,
Cooper,
J. Med.,
Schettler
891
and J.H.
0.
New
Atherosclerosis,
and J. Porath,
Nillius,
Lees,
Hedstrand,
D. Mason
Carlson,
Eder
J. Lipid AX&I
Salel,
(1970)
6
R.S.
H.
Heidelberg,
A.
L.A.
Organ..
and
and
U. Rosenqvist.
Shore,
Beaumont,
Health
Levy
Carlson
1 (1971)
4 (1967)
503 381
Acta
Endocrinol.,
Suppl.,
174
Biophys.
Acta.
(1975)
247
379
(1973)
1
Bull.
1 World